The sum of all palindromic numbers from 1001 to 9999 is 495000.
The same as the number of two-digit numbers, since the last two digits must the same as the first two, only reversed. So I'll say there are 100 four-digit palindromes.
The same as the number of two-digit numbers, since the last two digits must the same as the first two, only reversed. So I'll say there are 100 four-digit palindromes.
Any pair of digits (not including 0), can be used to generate 14 four-digit numbers. If one of the digits is 0, only seven will start with a non-zero digit.
There are 900 of them.
1
The same as the number of two-digit numbers, since the last two digits must the same as the first two, only reversed. So I'll say there are 100 four-digit palindromes.
The same as the number of two-digit numbers, since the last two digits must the same as the first two, only reversed. So I'll say there are 100 four-digit palindromes.
An eight digit number with one zero cannot remain the same when its digits are reversed. It must have an even number of 0s.
987654
2
Any pair of digits (not including 0), can be used to generate 14 four-digit numbers. If one of the digits is 0, only seven will start with a non-zero digit.
It is 987654321.
There are 900 of them.
The number of six digit numbers that you can make from ten different digits ifrepetitions of same digit on the six digit number is allowed is 1 000 000 numbers(including number 000 000).If no repetitions of the the same digit are allowed then you have:10P6 = 10!/(10-6)! = 151 200 different six digit numbers(six digit permutations form 10 different digits).
1
Exactly 2: 243 of them.
The same way you kfind it for 2 & 1 digits. :)