Alright, let's work through 1878 times 9901 step by step
1878 × 9901 = 9901 × (1878)
+ 9901 × 8 that equals 79208
+ 9901 × 70 producing 693070
+ 9901 × 800 producing 7920800
+ 9901 × 1000 that is equal 9901000

= 18594078
