How to Get e on a Calculator

Updated 5 November 2026 · Standard formula, shown below

To get the mathematical constant e on a calculator, use its dedicated e key or evaluate e raised to zero. The result is approximately 2.718281828; the exact steps depend on your calculator, and scientific calculators usually provide a direct key or an exponential function.

What You’ll Need

A scientific calculator, physical or on-screen, with an e key, an e^x function, or a general power function.
If you are using a basic calculator without those functions, a way to use the limit or series approximation described below.

Step-by-Step

Identify which e you need. In mathematics, lowercase e is Euler’s number, about 2.71828. It is different from the letter E that some calculators show in scientific notation, such as 3E5, which means 3 × 10⁵ (300,000). If a problem asks for e, you usually want the constant, not an exponent marker.
Look for the dedicated constant key. On a scientific calculator, inspect the keys for e or a secondary label such as e^x. A secondary function is commonly accessed with a 2nd, SHIFT, or similar key, but the labeling and key sequence vary by model. Check the calculator’s printed key labels or its manual rather than assuming a universal button combination.
Enter the constant. If a key directly inserts e, press it and then press = if your calculator requires evaluation. The display should show a value near 2.718281828. Some calculators show fewer digits, depending on screen space and display settings.
Use the exponential function if there is no standalone e key. Find e^x, which means e raised to the power x. Enter 0 as the exponent, then evaluate: e⁰ = 1, so this gives 1, not e. To obtain e through this function, enter an exponent of 1: e¹ = e. Follow the calculator’s input order: some models require entering 1 before pressing e^x, while others open an exponent field after you press the function.
Try a general power key if necessary. If the calculator has neither a direct constant key nor e^x, but does have a power function, compute e as e¹ only if the constant is available through a secondary key or menu. A power key by itself cannot create the number e; it needs a base value. Look through the calculator’s function menu or help documentation for constants.
Check the displayed value. The result should start with 2.718. If you see 1, you likely evaluated e⁰; if you see a different number, check whether the calculator applied a different function or whether you entered a value other than 1 as the exponent.
Copy enough digits for your work. For a typical hand calculation, 2.71828 is often sufficient, but follow the precision requested by your assignment or application. Keep the calculator’s full stored value when possible and round only the final result, since rounding intermediate values can affect later calculations.

Important correction: The shortcut through the exponential function is e¹, not e⁰. The latter equals 1. If your device offers a dedicated e constant, use that instead.

Common Mistakes

Confusing e with E in scientific notation. A display such as 2.718E0 means 2.718 × 10⁰, or 2.718. Here E marks a power of ten; it is not the mathematical constant key.
Using the wrong exponent. The constant is e¹. Entering an exponent of 0 produces 1, while an exponent of 2 produces about 7.389.
Mixing up e and the natural logarithm. The ln key calculates the natural logarithm of a number. It does not simply display e. For example, ln(e) = 1, while e itself is about 2.71828.
Pressing the wrong secondary-function key. Key labels and input order differ by calculator. A key’s shifted label may require 2nd or SHIFT; pressing the main key alone may perform another operation.
Rounding too early. Using 2.7 instead of 2.71828 can noticeably change results in repeated calculations, especially when e is raised to a power. Use the built-in constant where possible.

Tips

Look for e as a constant, and distinguish it from e^x, which is a function that needs an exponent.
Use e^1 when your calculator provides an exponential function but no direct constant key.
If you need a specific number of decimal places, set the display format if available, but remember that display rounding may not change the value held internally.
For a quick check, remember that e is between 2 and 3, and more precisely between 2.718 and 2.719.
On a phone or computer calculator, switch to a scientific or advanced layout if the standard keypad does not show constants or exponent functions.

Troubleshooting

The result is 1: You probably entered e⁰. Clear the entry and evaluate e¹, or locate the dedicated e constant.

The display shows an error: Clear the expression and start again. Make sure the exponent is entered in the correct order for your calculator and that no incomplete operation is left on the screen. Consult its manual if the function uses an unfamiliar entry method.

You cannot find an e key: Search for e^x, a constants menu, or a scientific/advanced mode. If none is available, the device may be too basic for direct calculation; use a scientific calculator or a reliable calculator app with the constant.

You see a value like 2.718E0: This is a valid scientific-notation display. The E0 means multiply by 10 to the zero power, so the value is 2.718. Adjust the number format if you want ordinary decimal notation.

Your answer differs in the last digits: Check display precision and rounding. Calculators may show different numbers of digits, but the value should begin 2.7182818. Keep full precision during calculations and round only when reporting the final answer.

Frequently Asked Questions

What is e on a calculator?
It is Euler’s number, a mathematical constant approximately equal to 2.718281828. It is used in exponential growth, logarithms, and many other areas of mathematics.

How do I type e on a scientific calculator?
Use the labeled e constant key if available. Otherwise, use the e^x function with an exponent of 1, following the input order for your model.

Is e the same as the E in 1.2E3?
No. In scientific notation, E means “times ten to the power of.” Thus 1.2E3 means 1.2 × 10³, or 1,200.

Is e the same as pi?
No. They are different constants: e is about 2.71828, while pi is about 3.14159.

Why does the ln button not give me e?
ln finds the natural logarithm of the number you enter. To get e, use its constant key or calculate e¹. The identity ln(e) = 1 explains why applying ln to e returns 1.

How many digits of e should I use?
Use the calculator’s full precision when possible. For a simple final answer, follow the precision required by the problem; if none is given, 2.71828 is a useful approximation.

Method: the standard formula for this calculation, rounded as each result states. See how the calculators work or report an error.