Alright, let's work through 1836 times 7145 step by step
1836 × 7145 = 7145 × (1836)
+ 7145 × 6 which equals 42870
+ 7145 × 30 what gives us 214350
+ 7145 × 800 yielding 5716000
+ 7145 × 1000 producing 7145000

= 13118220
