It is actually very simple, just take 10 to the square root of four.
10^4
There are 625 of them - too many to list.
9,000
The numbers from 1000 to 9999 are all 4 digits, as are -1000 to -9999. Therefore there are 18,000 four-digit numbers in all.
The numbers from 1000 to 9999 are all 4 digits, as are -1000 to -9999. Therefore there are 18,000 four-digit numbers in all.
2240
Any four-digit number that ends with 0, or with 5: 1000, 1005, 1010, 1015, ... 9990, 9995. If you want to have the complete list, I'll leave this fun part to you. Better write a computer program to list them.
Nope, look at 1000, this is a 4 digit number and we can't list it with 1,2,3, and 4
The number of four-digit combinations is 10,000 .Stick a '3' before each of them, and you have all the possible 5-digit combinations that start with 3.There are 10,000 of them. They run from 30,000 to 39,999 .
5*5*4*4 = 400
9
The four-digit numbers that can be formed using the digits 6, 7, 8, and 9, without repetition, are all the permutations of these four digits. There are 24 possible combinations, including numbers like 6789, 6798, 6879, and so on. Essentially, any arrangement of these four digits constitutes a valid four-digit number.
Even numbers are divisible by two, and half of all numbers are even, so there is a 50 percent chance that a four-digit number is divisible by two.