Alright, let's work through 1620 times 7422 step by step
1620 × 7422 = 7422 × (1620)
+ 7422 × 0 that results in 0
+ 7422 × 20 that results in 148440
+ 7422 × 600 which equals 4453200
+ 7422 × 1000 that equals 7422000

= 12023640
