How many different pairs of numbers (s, t) such that s = 2t 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
Given s=2t   t can take 0,1,2,3,4   and so s = 0,3,6,9   5 such pairs can be formed.   answer 5
<result>E</result>
How many different pairs of numbers (s, t) such that s = 2t can be obtained if s and t are selected from the set of number {0, 1, 2, 3, 4, 5, 6, 7, 8, 9}