Question

1+4=5 2+5=12 3+6=21 8+11=?

Answer 1

I think the pattern is that you multiply the first number by the second , then add the first number. SO:
e.g. for the first one 1 x 4 = 4 , 4 + 1 = 5
for the second one 2 x 5 = 10, 10 + 2 = 12...
So for 8+11:
you do 8 x 11 = 88 , 88 + 8 = 96