Alright, let's work through 2155 times 1640 step by step
2155 × 1640 = 1640 × (2155)
+ 1640 × 5 resulting in 8200
+ 1640 × 50 giving us 82000
+ 1640 × 100 giving us 164000
+ 1640 × 2000 which equals 3280000

= 3534200
