Alright, let's work through 2788 times 4639 step by step
2788 × 4639 = 4639 × (2788)
+ 4639 × 8 what gives us 37112
+ 4639 × 80 which equals 371120
+ 4639 × 700 giving us 3247300
+ 4639 × 2000 resulting in 9278000

= 12933532
