No problem, we've got 3970 and 7870 to multiply
3970 × 7870 = 7870 × (3970)
+ 7870 × 0 that equals 0
+ 7870 × 70 giving us 550900
+ 7870 × 900 that equals 7083000
+ 7870 × 3000 which equals 23610000

= 31243900
