can you solve a ~ b = d ?

Question

Here some definitions:
27 ~ 04 = 280
15 ~ 73 = 157
89 ~ 63 = 2748
12 ~ 34 = 83
56 ~ 78 = 4835

Please Mr. Euler, what is a ~ b?

Answer 1

27 ~ 04--> 7*4 & 2*0 = 28 & 0 = 280
15 ~ 73--> 5*3 & 1*7 = 15 & 7 = 157
89 ~ 63 --> 9*3 & 8*6 = 27 & 48 = 2748
12 ~ 34 --> 2*4 & 1*3 = 8 & 3 = 83
56 ~ 78 --> 6*8 & 5*7= 48 & 35 = 4835
a=a1a2, b=b1b2 => a~b=a2*b2 & a1*b1