Alright, let's work through 1640 times 2623 step by step
1640 × 2623 = 2623 × (1640)
+ 2623 × 0 resulting in 0
+ 2623 × 40 that equals 104920
+ 2623 × 600 that results in 1573800
+ 2623 × 1000 that results in 2623000

= 4301720
