Alright, let's work through 78561055 times 72820020 step by step
78561055 × 72820020 = 72820020 × (78561055)
+ 72820020 × 5 which equals 364100100
+ 72820020 × 50 giving us 3641001000
+ 72820020 × 000 which equals 0
+ 72820020 × 1000 what gives us 72820020000
+ 72820020 × 60000 that equals 4369201200000
+ 72820020 × 500000 that is equal 36410010000000
+ 72820020 × 8000000 which equals 582560160000000
+ 72820020 × 70000000 yielding 5097401400000000

= 5720817596321100
