Alright, let's work through 1115 times 1158 step by step
1115 × 1158 = 1158 × (1115)
+ 1158 × 5 yielding 5790
+ 1158 × 10 giving us 11580
+ 1158 × 100 that is equal 115800
+ 1158 × 1000 which equals 1158000

= 1291170
