Alright, let's work through 81215997 times 79910254 step by step
81215997 × 79910254 = 79910254 × (81215997)
+ 79910254 × 7 resulting in 559371778
+ 79910254 × 90 that equals 7191922860
+ 79910254 × 900 that equals 71919228600
+ 79910254 × 5000 which equals 399551270000
+ 79910254 × 10000 producing 799102540000
+ 79910254 × 200000 giving us 15982050800000
+ 79910254 × 1000000 what gives us 79910254000000
+ 79910254 × 80000000 which equals 6392820320000000

= 6489990949133238
