Alright, let's work through 1989 times 9090 step by step
1989 × 9090 = 9090 × (1989)
+ 9090 × 9 resulting in 81810
+ 9090 × 80 what gives us 727200
+ 9090 × 900 that equals 8181000
+ 9090 × 1000 producing 9090000

= 18080010
