Alright, let's work through 9004 times 8791 step by step
9004 × 8791 = 8791 × (9004)
+ 8791 × 4 producing 35164
+ 8791 × 00 giving us 0
+ 8791 × 000 that is equal 0
+ 8791 × 9000 producing 79119000

= 79154164
