No problem, we've got 8491 and 6640 to multiply
8491 × 6640 = 6640 × (8491)
+ 6640 × 1 which equals 6640
+ 6640 × 90 resulting in 597600
+ 6640 × 400 resulting in 2656000
+ 6640 × 8000 that is equal 53120000

= 56380240
