Alright, let's work through 1644 times 2407 step by step
1644 × 2407 = 2407 × (1644)
+ 2407 × 4 giving us 9628
+ 2407 × 40 what gives us 96280
+ 2407 × 600 which equals 1444200
+ 2407 × 1000 resulting in 2407000

= 3957108
