Alright, let's work through 1887 times 5121 step by step
1887 × 5121 = 5121 × (1887)
+ 5121 × 7 what gives us 35847
+ 5121 × 80 that is equal 409680
+ 5121 × 800 resulting in 4096800
+ 5121 × 1000 that equals 5121000

= 9663327
