Explanation:
Find the two closest square numbers to 1659.
40*40=1600
41*41=1681
Decide much closer to either 1600 or 1681 is 1659.
If it is exactly halfway between the two numbers, the square root is 40.5.
If it is closer to 1600, the sq rt decimal is between 1 and 4.
If it is closer to 1681, the sq rt decimal is between 6 and 9.
