Alright, let's work through 83801605 times 20377947 step by step
83801605 × 20377947 = 20377947 × (83801605)
+ 20377947 × 5 resulting in 101889735
+ 20377947 × 00 giving us 0
+ 20377947 × 600 that equals 12226768200
+ 20377947 × 1000 resulting in 20377947000
+ 20377947 × 00000 yielding 0
+ 20377947 × 800000 that results in 16302357600000
+ 20377947 × 3000000 which equals 61133841000000
+ 20377947 × 80000000 producing 1630235760000000

= 1707704665204935
