How many different four digit numbers can be made using the digits 1, 2, 3, 4, 5, 6. If no number can be used more than once.

combinations of 6 taken four at a time

same method as your other problem
6*5/2 = 15

To find the number of different four-digit numbers that can be made using the digits 1, 2, 3, 4, 5, and 6 without repetition, we can use the concept of permutations.

In this case, since we want to find four-digit numbers, the first digit can take any of the six given digits. After choosing the first digit, we have only five digits left to choose from for the second digit, four digits left for the third digit, and three digits left for the fourth digit.

To calculate the total number of different four-digit numbers, we multiply the number of choices for each digit:

Total number of different four-digit numbers = 6 * 5 * 4 * 3 = 360

Therefore, there are 360 different four-digit numbers that can be made using the digits 1, 2, 3, 4, 5, and 6 without repetition.