Alright, let's work through 81553801 times 83379931 step by step
81553801 × 83379931 = 83379931 × (81553801)
+ 83379931 × 1 producing 83379931
+ 83379931 × 00 giving us 0
+ 83379931 × 800 resulting in 66703944800
+ 83379931 × 3000 giving us 250139793000
+ 83379931 × 50000 which equals 4168996550000
+ 83379931 × 500000 what gives us 41689965500000
+ 83379931 × 1000000 yielding 83379931000000
+ 83379931 × 80000000 that is equal 6670394480000000

= 6799950300167731
