10001
The nearest number whose square ≤ 10000 is 100. Then the greatest odd number less that 100 is 99 so there are 50 odd numbers in the range 1- 99 inclusive whose squares are less than 10000.
100. Palindromic numbers for the range 10000 to 20000 are 5 digits numbers of the form abcba. The first digit ('a') must be '1'. There are 10 possible digits for 'b' (0-9) and for each of these 10 possible digits for 'c' Thus there are 1 x 10 x 10 = 100 palindromic numbers between 10000 and 20000.
20 number
There are 2704 of them between 1000 and 10000 inclusive.
10001
Infinitely many. There are a 100 perfect squares.
The answer to this is .... all the numbers between 999 and 10000
89999 Any whole number above 99999 has 6 or more digits, and any whole number below 10000 has 4 or less digits. Since there are only whole numbers involved, it is a simple subtraction of 10000 from 99999.
8 digits will generate over 40,000 permutations.
The nearest number whose square ≤ 10000 is 100. Then the greatest odd number less that 100 is 99 so there are 50 odd numbers in the range 1- 99 inclusive whose squares are less than 10000.
There are 3598 numbers between 10000 and 99999 which are divisible by 25. They are elements of the set of numbers of the form 25*k, where k is an integer between 41 and 3999 (inclusive).
100. Palindromic numbers for the range 10000 to 20000 are 5 digits numbers of the form abcba. The first digit ('a') must be '1'. There are 10 possible digits for 'b' (0-9) and for each of these 10 possible digits for 'c' Thus there are 1 x 10 x 10 = 100 palindromic numbers between 10000 and 20000.
10001
10000.......1(including 198 zero between 1s)
20 number
90000. With 10 digit palindromes, the last 5 digits are the same as the first 5 digits in reverse, eg 12345 54321. So it comes down to how many 5 digit numbers are there? They are the numbers "10000" to "99999", a total of 99999 - 10000 + 1 = 90000.