Alright, let's work through 78727875 times 72917720 step by step
78727875 × 72917720 = 72917720 × (78727875)
+ 72917720 × 5 giving us 364588600
+ 72917720 × 70 resulting in 5104240400
+ 72917720 × 800 that equals 58334176000
+ 72917720 × 7000 that is equal 510424040000
+ 72917720 × 20000 that equals 1458354400000
+ 72917720 × 700000 yielding 51042404000000
+ 72917720 × 8000000 resulting in 583341760000000
+ 72917720 × 70000000 producing 5104240400000000

= 5740657145445000
