Alright, let's work through 81990939 times 66359724 step by step
81990939 × 66359724 = 66359724 × (81990939)
+ 66359724 × 9 that results in 597237516
+ 66359724 × 30 which equals 1990791720
+ 66359724 × 900 giving us 59723751600
+ 66359724 × 0000 resulting in 0
+ 66359724 × 90000 yielding 5972375160000
+ 66359724 × 900000 giving us 59723751600000
+ 66359724 × 1000000 resulting in 66359724000000
+ 66359724 × 80000000 that equals 5308777920000000

= 5440896082540836
