Alright, let's work through 1646 times 4947 step by step
1646 × 4947 = 4947 × (1646)
+ 4947 × 6 that is equal 29682
+ 4947 × 40 giving us 197880
+ 4947 × 600 that equals 2968200
+ 4947 × 1000 what gives us 4947000

= 8142762
