Alright, let's work through 7989 times 3870 step by step
7989 × 3870 = 3870 × (7989)
+ 3870 × 9 resulting in 34830
+ 3870 × 80 resulting in 309600
+ 3870 × 900 that equals 3483000
+ 3870 × 7000 giving us 27090000

= 30917430
