Alright, let's work through 83864231 times 80203629 step by step
83864231 × 80203629 = 80203629 × (83864231)
+ 80203629 × 1 what gives us 80203629
+ 80203629 × 30 resulting in 2406108870
+ 80203629 × 200 that results in 16040725800
+ 80203629 × 4000 what gives us 320814516000
+ 80203629 × 60000 resulting in 4812217740000
+ 80203629 × 800000 giving us 64162903200000
+ 80203629 × 3000000 that is equal 240610887000000
+ 80203629 × 80000000 yielding 6416290320000000

= 6726215669494299
