No problem, we've got 5001 and 8001 to multiply
5001 × 8001 = 8001 × (5001)
+ 8001 × 1 that results in 8001
+ 8001 × 00 producing 0
+ 8001 × 000 that results in 0
+ 8001 × 5000 what gives us 40005000

= 40013001
