That would be every number from 20 to 99 followed by the number backward (2002, 2112, 2222, 2332, ..., 9779, 9889, 9999). The quantity is 99 - 19 or 80.
Ten
5
The next palindromic years are going to be 2112 and 2222. There is a 100 year difference between the two.
1. 1991 is the only number I think.
There are 90 palindromic numbers between 100 and 1000
infinite
A palindromic number is a number that remains the same when its digits are reversed. Between 1000 and 2000, the possible palindromic numbers have the form "ABBA" where A and B are digits from 1 to 9. There are 9 options for A (1-9) and 10 options for B (0-9), but we exclude the case where A is 0. Therefore, there are 9 * 10 = 90 palindromic numbers between 1000 and 2000.
To be palindromic, the year must be of the form XYYX where X and Y are digits, so we need only consider the first half of the number, namely the XY and the question becomes how many numbers XY are there between 20 and 99 such that XYYX is between 2000 and 9999.The answer depends upon the definition of "between":If "between" means strictly between, that is the year cannot be 2000 or 9999XY = 20 ⇒ 2002 > 2000 so allowed XY = 99 ⇒ 9999 = 9999 so not allowed⇒ number of years is 99 - 20 = 79If "between" means between but also including the limits, that is the year could be 2000 or 9999XY = 20 ⇒ 2002 > 2000 so allowed XY = 99 ⇒ 9999 = 9999 so still allowed⇒ number of years is 99 - 20 + 1 = 80
A palindromic number can have as few as one digit, and as many as infinity. The smallest palindromic number is zero and the largest is '999... to infinity'.
90
9
There are 900000 of them.