Let's calculate 1664 x 7815
1664 × 7815 = 7815 × (1664)
+ 7815 × 4 which equals 31260
+ 7815 × 60 that is equal 468900
+ 7815 × 600 giving us 4689000
+ 7815 × 1000 that results in 7815000

= 13004160
