A really simple mod you can use to make calculations in chat and not exit minecraft, not much to say.

Explanation (can be viewed ingame using /calc) : How to use the calculator:

To perform a calculation, type your message starting with = followed by your expression.

Example: = 3+4*2

Notes:

Use * or x for multiplication.

You can group expressions using parentheses (), curly braces {}, or square brackets [] interchangeably.

Supported operators: +, -, *, x, /, ^ (power).

Functions like sqrt or sin are not supported.

Make sure your expression is written correctly to avoid errors.

Can be used in modpacks without asking me, informing me would be nice though.