Answer
$0.1$
Work Step by Step
Step 1. There are 900 three-digit numbers (100 to 999).
Step 2. To form a three-digit number that reads the same forward and backward, the choice of first (thus the third) digit is $9$ (1-9) and the choice of the middle number is $10$ (0-9). Thus there are $90$ possibilities.
Step 3. The probability of finding such a number is $\frac{90}{900}=0.1$
