We're going to solve 6439 multiplied by 1820
6439 × 1820 = 1820 × (6439)
+ 1820 × 9 which equals 16380
+ 1820 × 30 what gives us 54600
+ 1820 × 400 that is equal 728000
+ 1820 × 6000 yielding 10920000

= 11718980
