Alright, let's work through 6839 times 1243 step by step
6839 × 1243 = 1243 × (6839)
+ 1243 × 9 what gives us 11187
+ 1243 × 30 that equals 37290
+ 1243 × 800 that equals 994400
+ 1243 × 6000 resulting in 7458000

= 8500877
