We're going to solve 9921 multiplied by 8220
9921 × 8220 = 8220 × (9921)
+ 8220 × 1 resulting in 8220
+ 8220 × 20 giving us 164400
+ 8220 × 900 yielding 7398000
+ 8220 × 9000 producing 73980000

= 81550620
