How many different pairs of numbers (s, t) such that s = 3t can be obtained if s and t are selected from the set of number {0, 1, 2, 3, 4, 5, 6, 7, 8, 9}  Pick
A) 1  B) 2  C) 3  D) 4  E) 5
s = 3t.   So, s/3 = t   That means s is divisible by 3.   Only 0, 3, 6, 9 are divisible by 3.   Hence option (4).
<result>D</result>
How many different pairs of numbers (s, t) such that s = 3t can be obtained if s and t are selected from the set of number {0, 1, 2, 3, 4, 5, 6, 7, 8, 9}