Alright, let's work through 66100139 times 87898989 step by step
66100139 × 87898989 = 87898989 × (66100139)
+ 87898989 × 9 yielding 791090901
+ 87898989 × 30 that is equal 2636969670
+ 87898989 × 100 producing 8789898900
+ 87898989 × 0000 that equals 0
+ 87898989 × 00000 what gives us 0
+ 87898989 × 100000 that results in 8789898900000
+ 87898989 × 6000000 yielding 527393934000000
+ 87898989 × 60000000 what gives us 5273939340000000

= 5810135390859471
