Alright, let's work through 7786 times 1638 step by step
7786 × 1638 = 1638 × (7786)
+ 1638 × 6 giving us 9828
+ 1638 × 80 yielding 131040
+ 1638 × 700 yielding 1146600
+ 1638 × 7000 that is equal 11466000

= 12753468
