Alright, let's work through 3987 times 1266 step by step
3987 × 1266 = 1266 × (3987)
+ 1266 × 7 yielding 8862
+ 1266 × 80 yielding 101280
+ 1266 × 900 resulting in 1139400
+ 1266 × 3000 that equals 3798000

= 5047542
