Alright, let's work through 2521 times 2878 step by step
2521 × 2878 = 2878 × (2521)
+ 2878 × 1 that is equal 2878
+ 2878 × 20 that equals 57560
+ 2878 × 500 producing 1439000
+ 2878 × 2000 giving us 5756000

= 7255438
