No problem, we've got 8428 and 9990 to multiply
8428 × 9990 = 9990 × (8428)
+ 9990 × 8 yielding 79920
+ 9990 × 20 that results in 199800
+ 9990 × 400 that equals 3996000
+ 9990 × 8000 giving us 79920000

= 84195720
