Calculate the numerical approximation of the square root of the desired number and estimate where it would be on the number line. , so, depending on the precision of your representation of a number line, pick a spot that would be close to that number and that's it. For example, if you just have a number line marked with whole numbers, then you would find a spot that is about 4 tenths of the way from the 1 to the 2, and then go just a little bit closer to 2, but certainly less than half-way from the 1 to the 2 and you will be close to the square root of 2 -- close enough anyway.

Awesome Guy XD