Alright, let's work through 1974 times 789 step by step
1974 × 789 = 789 × (1974)
+ 789 × 4 that is equal 3156
+ 789 × 70 giving us 55230
+ 789 × 900 yielding 710100
+ 789 × 1000 giving us 789000

= 1557486
