The GCD (a, b) = 6, the LCM (a, b) = 180. Find the least possible value of a+b.

The factors of 180 are

(1, 180), (2, 90), (3, 60), (4, 45), (5, 36), (6, 30), (9, 20), (10, 18), (12, 15).

The GCD of 6 is the largest positive integer that divides 180.

Therefore the required factors of 180 are a=6 and b=30 or vice versa.

a + b = 6 + 30 = 36

Answer: 36