@ossobuco,
I thought 11 would get some people. It's a maths/computing joke
Oct and Dec are computing ways of describing base 8 and base 10 numbers.
in Base 10 the rightmost digit is how many ones then the next left is the number of 10s and the next the number of 100s
So 127 in base 10 (or DEC) is
100 + 2x20 + 7x1
Oct is base 8, so the rightmost digit is the number of ones, the next left is the number of 8s and the next the number of 64s
so 127 in base 8 (or OCT)is
1x64 + 2x8 + 7x8
which is 136 in base 10 (or DEC)
Bringing it all home
OCT 31 is
3x8 + 1
and
DEC 25 is
2x10 +5
Thus OCT31 = DEC25
If you're nice to me I'll explain binary and why all computers only use 1's and 0's