Answer:
99.
Explanation:
A palindrome number is one that can be read in the same way both from the front and from the back. A clear example is the number 242, which starts and ends in the same way from the front or back.
Between 10 and 100, there are 9 palindromes, from 11 to 99. In turn, between 100 and 200, 200 and 300 and so on, each hundred has within it 10 palindromes (101, 111, 121, 131, 141 , 151, 161, 171, 181 and 191, for example).
Therefore, considering the 9 hundreds between 100 and 1000, there will be 90 palindromes, which added to the 9 between 10 and 100 give a total of 99 palindromes.