Alright, let's work through 2181 times 1815 step by step
2181 × 1815 = 1815 × (2181)
+ 1815 × 1 giving us 1815
+ 1815 × 80 that is equal 145200
+ 1815 × 100 which equals 181500
+ 1815 × 2000 resulting in 3630000

= 3958515
