Another way is to express the two numbers as a product of their prime factors.
240 = 2 x 2 x 2 x 2 x 3 x 5
1500 = 2 x 2 x 3 x 5 x 5 x 5
If you pair up a factor of 240 with the same factor of 1500, you find that 2 matches twice, 3 once and 5 once
so HCF = 2 x 2 x 3 x 5 = 60