Alright, let's work through 81641743 times 78575126 step by step
81641743 × 78575126 = 78575126 × (81641743)
+ 78575126 × 3 that is equal 235725378
+ 78575126 × 40 yielding 3143005040
+ 78575126 × 700 resulting in 55002588200
+ 78575126 × 1000 that equals 78575126000
+ 78575126 × 40000 yielding 3143005040000
+ 78575126 × 600000 giving us 47145075600000
+ 78575126 × 1000000 that equals 78575126000000
+ 78575126 × 80000000 resulting in 6286010080000000

= 6415010243084618
