Answer:
1188
Step-by-step explanation:
We multiply all three numbers together. There are two quick ways of doing this; both are shown below:$11\cdot 9 \cdot 12 = (10 + 1)\cdot 108 = 1080 + 108 = \boxed{1188}$$11\cdot 9 \cdot 12 = 99\cdot 12 = (100 - 1)\cdot 12 = 1200 - 12 = \boxed{1188}$
