link on demo: Antongron.github.io

Instruction forent get the square root:

1. enter number.
2. next click on √.
3. and then 2.
4. and finaly =. Also you can get cube root. Instruction to get it:
5. enter number.
6. next click on √.
7. and then 3.
8. and finaly =.

Instruction for work with negative numbers: Chose number and then click on "±" if you want to change it on negative. PS: if you wish, you also can change it back in positive number the same way.

Thanks for you cross-check!:)