Alright, let's work through 7791 times 1139 step by step
7791 × 1139 = 1139 × (7791)
+ 1139 × 1 yielding 1139
+ 1139 × 90 giving us 102510
+ 1139 × 700 producing 797300
+ 1139 × 7000 that equals 7973000

= 8873949
