Alright, let's work through 89883821 times 19899903 step by step
89883821 × 19899903 = 19899903 × (89883821)
+ 19899903 × 1 giving us 19899903
+ 19899903 × 20 giving us 397998060
+ 19899903 × 800 yielding 15919922400
+ 19899903 × 3000 resulting in 59699709000
+ 19899903 × 80000 yielding 1591992240000
+ 19899903 × 800000 resulting in 15919922400000
+ 19899903 × 9000000 that results in 179099127000000
+ 19899903 × 80000000 which equals 1591992240000000

= 1788679319169363
