# How can i build a calculator

Question:how can i build a working calculator

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First, design it of course. Then, if you’re wondering how to do the calculations, you can use the `eval` function in JavaScript. It takes in a string and outputs the mathematical solution. Example:

``````const answerToTwoPlusTwo = eval("2 + 2") // 4
``````

You can detect when your calculator buttons are clicked, and combine all of them into a string or array. Then when the user presses the equal sign, you can run `eval` and show them the result.

2 Likes

It looks like you are trying to build a calculator in python. (remember to include the language when asking questions.)
An easy way to do this is with the builtin `eval` function. It takes a string and evaluates it as if it is a python expression. It’s not perfect, but it works.

``````def calculate():
inp = input().replace('^', '**')  # exponentiation in python uses **, double asterisk
for character in inp:
if character.isalpha():  # no alphabet letters allowed
print('Invalid input')
return
try:
result = eval(inp)
@akunreseller439 You can use Python’s `math` module to run calculations too!