Find the least perfect square which is completely divisible by 8, 9 and 12.

144

LCM of 8, 9, 12 = 4 × 3 × 3 × 2 (It is not a perfect square)

                                   ↓

                                  × by 2 (To make it perfect square)

                                   ↓

                          4 × 3 × 3 × 2 × 2 = 144