Previously, when you would calculate the square root of 4, the result would be 1.99999999999999999989317180305609 which would be rounded to 2 when displayed, because we calculated enough digits to do the rounding correctly. However, as soon as you subtract 2, you would see the remaining digits.
After this update, the square root calculation now recognizes perfect squares and correctly returns exactly 2 for the square root of 4.
Source