Alright, let's work through 6638 times 630 step by step
6638 × 630 = 630 × (6638)
+ 630 × 8 that results in 5040
+ 630 × 30 giving us 18900
+ 630 × 600 that is equal 378000
+ 630 × 6000 which equals 3780000

= 4181940
