900 numbers
Assuming positive integers, and no leading zeros, the range of five digit numbers is 10000 to 99999. The ones that end in zero can be found by taking the four digit numbers: 1000 to 9999 and multiplying each by ten. {1000,1001, 1002, ...9999}, multiplied by ten is {10000,10010,10020,....99990}. There are 9000 of them.
There are 9 of them.
There are 168 = 4,294,967,296 such numbers.
13, 23, 43, 53, 73 & 83
All of the four-digit multiples of 400 end in 00.
There are 500000 such numbers.
All of them. There are roughly 45,000 5-digit odd numbers. None of them end in 0.
There are 5000 such strings.
30 of them.
All those that end with 0 or 5 are divisible by 5. That would be 1000, 1005, 1010, ... 9990, 9995. There are 900 such numbers.
No, there are composite numbers that end in every other digit.
That would be all the numbers that end with 0 or 5. So:* For the first digit, you have 9 options (digits 0-9). * For the second digit, you have 10 options. * For the third digit, you have 10 options. * For the fourth digit, you have 2 options (the digits 0 or 5). You can multiply all those together.