Alright, let's work through 78661309 times 8440835 step by step
78661309 × 8440835 = 8440835 × (78661309)
+ 8440835 × 9 yielding 75967515
+ 8440835 × 00 that results in 0
+ 8440835 × 300 resulting in 2532250500
+ 8440835 × 1000 that results in 8440835000
+ 8440835 × 60000 which equals 506450100000
+ 8440835 × 600000 resulting in 5064501000000
+ 8440835 × 8000000 what gives us 67526680000000
+ 8440835 × 70000000 that results in 590858450000000

= 663967130153015
