Alright, let's work through 84020645 times 63255311 step by step
84020645 × 63255311 = 63255311 × (84020645)
+ 63255311 × 5 that is equal 316276555
+ 63255311 × 40 yielding 2530212440
+ 63255311 × 600 that results in 37953186600
+ 63255311 × 0000 resulting in 0
+ 63255311 × 20000 that equals 1265106220000
+ 63255311 × 000000 what gives us 0
+ 63255311 × 4000000 that equals 253021244000000
+ 63255311 × 80000000 that equals 5060424880000000

= 5314752029895595
