Alright, let's work through 6991 times 1236 step by step
6991 × 1236 = 1236 × (6991)
+ 1236 × 1 yielding 1236
+ 1236 × 90 giving us 111240
+ 1236 × 900 that equals 1112400
+ 1236 × 6000 resulting in 7416000

= 8640876
