Square root Python 2.7.12

Question

Why does the math module return the wrong result?

First test

A = 12345678917
print \'A =\',A
B = sqrt(A**2)
print \'B =\',int(B)
         


        

Answer 1

If you want to calculate sqrt of really large numbers and you need exact results, you can use sympy:

import sympy

num = sympy.Integer(123456758365483459347856)

print(int(num) == int(sympy.sqrt(num**2)))