D - 4M is the 13th letter of the alphabet
13 backwards is 31
It all makes sense
I - 9
S - 19
C - 3
O - 15
V - 22
E - 5
R - 18
Y - 25
4+9+19+3+15+22+5+18+15=120
Discovery has 9 letters.
120/9=13.3
13.3 backwards is 3.31..... well... close enough.