No problem, we've got 8140 and 8400 to multiply
8140 × 8400 = 8400 × (8140)
+ 8400 × 0 that is equal 0
+ 8400 × 40 that is equal 336000
+ 8400 × 100 that results in 840000
+ 8400 × 8000 giving us 67200000

= 68376000
