Alright, let's work through 1603 times 7897 step by step
1603 × 7897 = 7897 × (1603)
+ 7897 × 3 producing 23691
+ 7897 × 00 that equals 0
+ 7897 × 600 which equals 4738200
+ 7897 × 1000 what gives us 7897000

= 12658891
