We're going to solve 3145 multiplied by 4104
3145 × 4104 = 4104 × (3145)
+ 4104 × 5 yielding 20520
+ 4104 × 40 that equals 164160
+ 4104 × 100 that equals 410400
+ 4104 × 3000 giving us 12312000

= 12907080
