Alright, let's work through 3991 times 7323 step by step
3991 × 7323 = 7323 × (3991)
+ 7323 × 1 what gives us 7323
+ 7323 × 90 giving us 659070
+ 7323 × 900 which equals 6590700
+ 7323 × 3000 that equals 21969000

= 29226093
