I have four pre-defined input keywords. (e.g num1, num2, etc) Based on these keywords the user will define a formula in a textbox.
Example:
num1 + num2 \* num3 \* (num3-num1)

Since this input will be taken from a textbox it will be a string.
How can convert these keywords from string to the variable name and execute the formula in my code?

I didn't find any suitable answer for this in other threads.

Any help is appreciated. Thanks