Alright, let's work through 1581 times 7791 step by step
1581 × 7791 = 7791 × (1581)
+ 7791 × 1 resulting in 7791
+ 7791 × 80 what gives us 623280
+ 7791 × 500 which equals 3895500
+ 7791 × 1000 producing 7791000

= 12317571
