Alright, let's work through 99815516 times 53501209 step by step
99815516 × 53501209 = 53501209 × (99815516)
+ 53501209 × 6 that results in 321007254
+ 53501209 × 10 which equals 535012090
+ 53501209 × 500 that is equal 26750604500
+ 53501209 × 5000 which equals 267506045000
+ 53501209 × 10000 that is equal 535012090000
+ 53501209 × 800000 resulting in 42800967200000
+ 53501209 × 9000000 that equals 481510881000000
+ 53501209 × 90000000 giving us 4815108810000000

= 5340250782958844
