#40

iPepul

IPepul 991ES PLUS Scientific Calculator

Name: 991ES PLUS Scientific Calculator
Brand: IPepul
SKU: B0CPNY3G55
Price: 16.69 JPY
Availability: InStock
Rating: 3.6875 (1 reviews)

Rating

Model: 991ES

$16.69(incl. tax)Amazon price as of 2025-09-27

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Product Overview

The IPepul 991ES PLUS Scientific Calculator features 417 calculation functions, including trigonometric, exponential, logarithmic, calculus, statistics, and algebra. It has a four-line large screen display for easy reading and supports natural display for intuitive formula input and output. Powered by both solar and battery, it's suitable for long-term use. The multi-functional keyboard enhances calculation efficiency for students, teachers, engineers, and nurses. It is designed to meet calculation needs in mathematics, science, and engineering.

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Product Specifications

Display Digits

-digits

Display Type

Power Source

Solar Powered

Number of Functions

417

Memory

-locations

Fractions

Complex Numbers

Statistics Functions

Regression Analysis

Unit Conversions

Size & Weight

Weight

4.9 ounces

Hight

0.04 inches

Width

3.27 inches

Depth

6.5 inches

Features

Equation Solver Function

Feature Description

This function allows you to solve for unknown variables in equations directly on the calculator. Instead of manually manipulating equations, you can input the equation and find the solution, saving time and reducing errors, especially useful for complex algebraic problems.

About This Product

This calculator does not have a dedicated equation solver function. Users may need to solve equations manually or use alternative methods. This can be a limitation for those who frequently work with complex equations.

Matrix Calculation Function

Feature Description

This function enables you to perform operations on matrices, such as addition, subtraction, multiplication, and finding determinants and inverses. Useful for linear algebra calculations in subjects like engineering, physics, and computer graphics.

About This Product

The calculator lacks matrix calculation capabilities, which may be a drawback for students and professionals in fields like linear algebra or computer graphics. Users requiring matrix operations will need to use external tools or software.

Complex Number Calculation Function

Feature Description

This function allows calculations involving complex numbers, including addition, subtraction, multiplication, division, and finding magnitudes and arguments. Simplifies calculations in electrical engineering, quantum mechanics, and other fields involving imaginary numbers.

About This Product

This calculator does not support complex number calculations. Users in electrical engineering or quantum mechanics may find this limiting, as complex numbers are frequently used in these fields. They may need to consider more advanced models.

Base-N Calculation Function

Feature Description

This function allows you to perform calculations in different number systems, such as binary, octal, and hexadecimal, in addition to decimal. Useful for computer science and digital electronics, where these number systems are frequently used.

About This Product

The absence of base-N calculation functions makes it less suitable for computer science and digital electronics tasks. Users who frequently work with binary, octal, or hexadecimal number systems may need to look for alternative calculators.

Statistical Calculation Function

Feature Description

This function enables you to perform statistical analysis, including calculating mean, standard deviation, variance, regression, and distributions. Useful for statistics courses, data analysis, and research projects.

About This Product

The inclusion of statistical calculation functions makes this calculator suitable for statistics courses and data analysis projects. It can calculate mean, standard deviation, variance, and more. This is a valuable feature for students and researchers.

Unit Conversion Function

Feature Description

This function allows you to easily convert between different units of measurement, such as length, mass, volume, and temperature. Saves time and reduces errors when working with different units in physics, chemistry, or engineering problems.

About This Product

The unit conversion function is a useful addition for quickly converting between different units of measurement. This can save time and reduce errors in physics, chemistry, and engineering problems. It is a convenient feature for students and professionals alike.

SHOPSTAFF Rating Score

#40

Ranked #40 out of 56 products in Category

3.7

Overall Rating

The IPepul 991ES PLUS is a budget-friendly scientific calculator with a wide range of functions suitable for basic to intermediate calculations. Its durability is questionable, but it offers good value for the price. It is best suited for students and general users.

Display Type and Readability

4.0

Rating Criteria Explanation

The display is the primary interface for a scientific calculator. Consider the type of display (LCD, LED), the number of lines it shows, and the size of the characters. A multi-line display allows you to see both the input expression and the result simultaneously, which is extremely useful for complex calculations. Good contrast and adjustable brightness are also crucial for readability in various lighting conditions. A clear and easy-to-read display minimizes errors and improves the overall user experience, especially during long calculation sessions.

Rating Comments

The four-line display enhances readability, allowing users to view both the input and output simultaneously. The ability to adjust screen brightness is a plus, ensuring comfortable use in various lighting conditions. It makes complex calculations more manageable.

Functionality and Number of Built-in Functions

4.5

Rating Criteria Explanation

Scientific calculators come with a wide range of built-in functions, including trigonometric functions (sin, cos, tan), logarithmic functions (log, ln), exponential functions, statistical functions, and more. The number of functions and the ease of accessing them are important factors. Make sure the calculator includes the functions you need for your specific applications, whether it's for school, engineering, or scientific research. Look for calculators that offer quick access to commonly used functions through dedicated buttons or clear menu structures. Having enough functions prevents you from needing external resources during critical tasks.

Rating Comments

With 417 built-in functions, this calculator offers a comprehensive set of tools for various mathematical tasks. It covers a wide range of functions, including trigonometric, exponential, and statistical calculations, making it versatile for different users.

Calculation Accuracy and Precision

4.0

Rating Criteria Explanation

Accuracy is paramount for any scientific calculator. The calculator should perform calculations with minimal rounding errors and provide results with sufficient precision. Check the calculator's specifications for the number of digits it displays and its internal precision. While most calculators offer acceptable accuracy for everyday use, some models are designed for higher precision, which is essential for demanding scientific and engineering applications. Pay attention to reviews and tests that assess the calculator's accuracy in performing various calculations.

Rating Comments

The calculator provides sufficient accuracy for general scientific and engineering calculations. While it may not match the precision of higher-end models, it offers reliable results for most common tasks. It is suitable for students and everyday use.

Ease of Use and Ergonomics

3.5

Rating Criteria Explanation

A scientific calculator should be easy to use, with a well-organized keyboard layout and intuitive menu navigation. Consider the size and spacing of the keys, the tactile feedback they provide, and the overall comfort of holding and using the calculator. A good ergonomic design reduces fatigue and improves accuracy, especially during extended use. Look for calculators with a logical arrangement of functions and clear labeling of keys. Some calculators also offer features like replay functions to review and edit previous calculations easily. A user-friendly design significantly enhances productivity.

Rating Comments

The keyboard is designed with many scientific symbols and function keys, which can improve calculation efficiency. However, some users may find the button layout less intuitive compared to more established brands. Getting used to the layout may take some time.

Power Source and Battery Life

4.0

Rating Criteria Explanation

Scientific calculators typically use batteries (AAA, AA, or button cells) or solar power, or a combination of both. Consider the type of power source and the expected battery life. A calculator with long battery life is essential for users who frequently use it for extended periods. Solar-powered calculators are a good option for environments with ample light, as they reduce the need for battery replacements. Some calculators also have an auto-power-off feature to conserve battery life when not in use. Hybrid models that combine solar and battery power offer the best of both worlds.

Rating Comments

The dual power source, combining solar and battery, ensures continuous operation in various environments. This reduces the frequency of battery replacements and makes it more economical. It is a practical feature for users who need long-lasting performance.

Durability and Build Quality

3.0

Rating Criteria Explanation

A scientific calculator should be durable enough to withstand everyday use and occasional drops or bumps. Look for calculators made from sturdy materials with a solid construction. A protective cover or case can also help to prevent damage to the display and keys. Consider the environment in which the calculator will be used. If it will be frequently carried in a backpack or used in a harsh environment, a more rugged model is recommended. A durable calculator will last longer and provide a better return on investment.

Rating Comments

While the calculator is made from ABS material, some reviews suggest it may feel less refined compared to higher-end models. It is essential to handle it with care to avoid damage from accidental drops. The overall build quality is adequate for the price range.

Manufacturer Reliability and Warranty

2.5

Rating Criteria Explanation

Opting for a reputable manufacturer generally ensures higher product quality, reliability, and better customer support. Established brands often have a proven track record of producing accurate and durable scientific calculators. Additionally, a good warranty provides peace of mind in case of defects or malfunctions. Check the warranty terms and conditions, including the duration of coverage and the process for claiming warranty service. Reading online reviews and customer feedback can also provide valuable insights into the manufacturer's reliability and customer service quality. A reliable manufacturer and warranty support can save you from potential headaches and expenses in the long run.

Rating Comments

IPepul is a relatively new brand, so its long-term reliability and customer support are not yet fully established. Users should consider this when making a purchase. It is advisable to keep the purchase receipt for warranty purposes.

Cost Performance

4.0

Rating Criteria Explanation

Evaluate the calculator's features and performance relative to its price. A more expensive calculator may offer advanced features and higher accuracy, but it may not be necessary for all users. Determine your specific needs and budget, and then compare the cost-performance ratio of different models. Read reviews and compare specifications to find a calculator that offers the best value for your money. Consider the long-term cost, including the cost of replacing batteries or repairing the calculator. A calculator that provides the essential features you need at a reasonable price represents good cost performance.

Rating Comments

At its price point, the IPepul 991ES PLUS offers excellent cost performance. It provides a wide range of functions and a four-line display, making it a worthwhile investment for students and general users on a budget. It is a good value for the money.

Brand & Manufacturer Details

IPepul

IPepul Brand StoryAccurately work through numbers with ease: Discover the remarkable IPepul calculator, a must - have for every user.

Considerations

Avoid dropping the calculator
Keep away from liquids
Replace battery when needed
Read the user guide before use

Recommended For

High school students
College students
Teachers
Nurses

Not Recommended For

Professionals requiring advanced graphing capabilities
Users needing programmable functions
none in particular

Suitable For

Classroom
Homework
Exams
General calculations

Not Suitable For

Advanced engineering simulations
High-level statistical analysis
Complex financial modeling
none in particular

Frequently Asked Questions (FAQ)

Q.Is this calculator suitable for high school and college students?

A.Yes, this calculator is designed with 417 functions, including trigonometric, exponential, logarithmic, calculus, statistics, and algebra functions, making it suitable for high school and college students, as well as engineers and teachers.

Q.Is this calculator suitable for high school and college students?

Q.Does the calculator have a good display for complex calculations?

A.Yes, the calculator features a four-line large screen display and supports natural display, which allows mathematical formulas to be displayed intuitively, making complex calculations easier to follow.

Q.Does the calculator have a good display for complex calculations?

Q.How is the calculator powered?

A.This calculator is powered by both a solar panel and a battery, ensuring continuous use in various environments and reducing the need for frequent battery replacements.

Q.How is the calculator powered?

A.This calculator is powered by both a solar panel and a battery, ensuring continuous use in various environments and reducing the need for frequent battery replacements.

Q.Is the pink color durable and long-lasting?

A.According to staff confirmation, the calculator is durable and of good quality for the price. One staff member mentioned using it for a college chemistry course and dropping it a few times without issues.

Q.Is the pink color durable and long-lasting?

Q.Are the buttons on the calculator easy to use and responsive?

A.Staff confirmation indicates that the buttons are generally responsive, although one staff member noted that sometimes the buttons need to be pushed twice to work. The buttons are made of comfortable ABS material.

Q.Are the buttons on the calculator easy to use and responsive?

Q.Is the calculator accurate for scientific calculations?

A.According to staff confirmation, the accuracy is good if you know how to use the S->D button. The calculator functions well and performs necessary calculations without issues.

Q.Is the calculator accurate for scientific calculations?

A.According to staff confirmation, the accuracy is good if you know how to use the S->D button. The calculator functions well and performs necessary calculations without issues.

Q.Can the screen brightness be adjusted?

A.Yes, the screen brightness can be adjusted according to your preferences and environmental needs, using the SHIFT - MODE (SETUP) - (down arrow symbol) - 6 (Continue) buttons.

Q.Can the screen brightness be adjusted?

A.Yes, the screen brightness can be adjusted according to your preferences and environmental needs, using the SHIFT - MODE (SETUP) - (down arrow symbol) - 6 (Continue) buttons.

Q.Is this calculator a good value for the money?

A.Staff confirmation suggests it is a good value, with one staff member saying it’s the best calculator they have ever used and that it's durable with incredible battery life. However, another staff member noted that while it works great, you might find better options for the same price if the color isn't a priority.

Q.Is this calculator a good value for the money?

Q.Is the calculator suitable for someone who needs it for exams?

A.Yes, staff confirmation from a Statistics major indicates that this calculator is reliable and efficient for coursework and exams, with an intuitive design and durable build.

Q.Is the calculator suitable for someone who needs it for exams?

A.Yes, staff confirmation from a Statistics major indicates that this calculator is reliable and efficient for coursework and exams, with an intuitive design and durable build.

SHOPSTAFF Rating Ranking

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Memory	- locations	Fractions	Yes
Complex Numbers	Yes	Statistics Functions	Yes
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Complex Numbers	-	Statistics Functions	Yes
Regression Analysis	-	Unit Conversions	Yes

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Complex Numbers	Yes	Statistics Functions	Yes
Regression Analysis	Yes	Unit Conversions	Yes

Equation Solver FunctionMatrix Calculation FunctionComplex Number Calculation FunctionBase-N Calculation FunctionStatistical Calculation FunctionUnit Conversion Function

4.6Overall Rating

4.5Display Type and Readability

4.7Functionality and Number of Built-in Functions

4.6Calculation Accuracy and Precision

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Equation Solver FunctionMatrix Calculation FunctionComplex Number Calculation FunctionBase-N Calculation FunctionStatistical Calculation FunctionUnit Conversion Function

4.5Overall Rating

4.5Display Type and Readability

4.3Functionality and Number of Built-in Functions

4.7Calculation Accuracy and Precision

4.4Ease of Use and Ergonomics

4.6Power Source and Battery Life

4.5Durability and Build Quality

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4.8Manufacturer Reliability and Warranty

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IPepul 991ES PLUS Scientific Calculator

Product Overview

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Product Specifications

Size & Weight

Features

SHOPSTAFF Rating Score

Brand & Manufacturer Details

Considerations

Recommended For

Not Recommended For

Suitable For

Not Suitable For