Alright, let's work through 1240 times 678 step by step
1240 × 678 = 678 × (1240)
+ 678 × 0 what gives us 0
+ 678 × 40 that results in 27120
+ 678 × 200 that equals 135600
+ 678 × 1000 yielding 678000

= 840720
