Alright, let's work through 6645 times 4272 step by step
6645 × 4272 = 4272 × (6645)
+ 4272 × 5 what gives us 21360
+ 4272 × 40 which equals 170880
+ 4272 × 600 giving us 2563200
+ 4272 × 6000 yielding 25632000

= 28387440
