Alright, let's work through 1989 times 7950 step by step
1989 × 7950 = 7950 × (1989)
+ 7950 × 9 what gives us 71550
+ 7950 × 80 what gives us 636000
+ 7950 × 900 what gives us 7155000
+ 7950 × 1000 what gives us 7950000

= 15812550
