Alright, let's work through 9981997 times 621088 step by step
9981997 × 621088 = 621088 × (9981997)
+ 621088 × 7 resulting in 4347616
+ 621088 × 90 giving us 55897920
+ 621088 × 900 which equals 558979200
+ 621088 × 1000 which equals 621088000
+ 621088 × 80000 what gives us 49687040000
+ 621088 × 900000 which equals 558979200000
+ 621088 × 9000000 yielding 5589792000000

= 6199698552736
