Here is how I got 96.
Obviously 1+4=5, but 2+5 does not =12, and 3+6 does not equal 21. So there is a hidden function going on.
I used the first number as a multiplier of the second number, then added the first number to that to get the answer.
1+(4 x 1)=5
2+(5 x 2)=12
3+(6 x 3)=21
8+(11 x 8)=96
Interestingly, if you do this equation starting at 0+3 and carry it on in the same progression from there, you will get a progression of uneven positive numbers in steps of two as the difference of the answers. I know, that is confusing. Let me show the work.
0+(3 x 0)=0
1+(4 x 1)=5 a difference of 5 from the answer before.
2+(5 x 2)=12 a difference of 7 from the answer before.
3+(6 x 3)=21 a difference of 9 from the answer before.
4+(7 x 4)=32 a difference of 11 from the answer before.
5+(8 x 5)=45 a difference of 13 from the answer before.
6+(9 x 6)=60 a difference of 15 from the answer before.
7+(10 x 7)=77 a difference of 17 from the answer before.
8+(11 x8)=96 a difference of 19 from the answer before. (Again interestingly, 19 is the answer to a normal 8+11 equation.)
and continue on in this pattern indefinitely.
NOTE: this is not a ground breaking revelation in mathematics,
! It's just something I found interesting.