Question

What number goes in the missing space? 5,2,10 3,3,9 2,6,?

Answer 1

2*6 is 12
so the answer is 12

Answer 2

you can notice the sequence:
5*2=10
3*3=9
following the same sequence:
2*6=12
therefore, the missing number is 12
(2,6,12)