90
40. Excluding numbers starting with 0.
The sum of all palindromic numbers from 1001 to 9999 is 495000.
Palindromic numbers between 100 and 600 are those that read the same forwards and backwards. The three-digit palindromic numbers in this range are 101, 111, 121, 131, 141, 151, 161, 171, 181, 191, 202, 212, 222, 232, 242, 252, 262, 272, 282, 292, 303, 313, 323, 333, 343, 353, 363, 373, 383, 393, 404, 414, 424, 434, 444, 454, 464, 474, 484, 494, 505, 515, 525, 535, 545, 555, 565, 575, 585, and 595. There are a total of 49 palindromic numbers between 100 and 600.
1001 - 1991, etc = 10, x (2,3,4,5,6,7,8,9) 8 = 80
24
40. Excluding numbers starting with 0.
there are 10 palindromic numbers between 9000 and 10000 9009,9119,9229,9339,9449,9559,9669,9779,9889,9999!!!
a 8-digits palindromic number is a number consisting of a 4-digits number written and then written backward, i.e. 1234 4321 so there are as many palindromic 8-digits numbers as 4-digits numbers so from 1000 to 9999, so there are 8999 palindromic 8 digits number (I assumed that 00011000 is not to be considered as a valid 8 digit number)
1001 is the smallest 4 digit palindromic number.
The sum of all palindromic numbers from 1001 to 9999 is 495000.
1001 - 1991, etc = 10, x (2,3,4,5,6,7,8,9) 8 = 80
24
17
3 digit numbers are lessthan 4 digit numbers
There are 2941 4-digit numbers such no two of its digits differ by 1.
-11
Assuming leading zeros don't count: 1001