No problem, we've got 5138 and 815 to multiply
5138 × 815 = 815 × (5138)
+ 815 × 8 what gives us 6520
+ 815 × 30 that is equal 24450
+ 815 × 100 which equals 81500
+ 815 × 5000 yielding 4075000

= 4187470
