Alright, let's work through 7874 times 2636 step by step
7874 × 2636 = 2636 × (7874)
+ 2636 × 4 producing 10544
+ 2636 × 70 that is equal 184520
+ 2636 × 800 which equals 2108800
+ 2636 × 7000 that is equal 18452000

= 20755864
