**Question:**

Find the least number of three digits which is perfect square.

**Solution:**

Let us make a list of the squares starting from 1.

12 = 1

22 = 4

32 = 9

42 = 16

52 = 25

62 = 36

72 = 49

82 = 64

92 = 81

102 = 100

The square of 10 has three digits. Hence, the least three-digit perfect square is 100.