Alright, let's work through 3031 times 6878 step by step
3031 × 6878 = 6878 × (3031)
+ 6878 × 1 resulting in 6878
+ 6878 × 30 which equals 206340
+ 6878 × 000 that equals 0
+ 6878 × 3000 yielding 20634000

= 20847218
