Download the Math Module from the AppStore and use that to implement the function sqrt.

Square root is probably the first function that Mendix decided not to implement. This is as far as it goes: https://docs.mendix.com/refguide/mathematical-function-calls

Also the function pow($yournumber, 0.5) does the trick.

If you only want to know how it can be calculated, here are some hints:

https://en.wikipedia.org/wiki/Methods_of_computing_square_roots

;-)

The documentation tells you how to calculate a square root in Mendix.

https://docs.mendix.com/refguide/mathematical-function-calls#8-4-square-root

It’s not stand-alone named function, but instead it’s a call to the pow function.