if digits can't be repeated, how many 4-digit numbers can be arranged using the digits 1, 3, 5, 7, and 9?
To find the number of 4-digit numbers that can be arranged using the digits 1, 3, 5, 7, and 9 without repetition, we can use the concept of permutation.
Permutation is used to calculate the number of ways objects can be arranged in a specific order. In this case, we want to find the number of ways we can arrange the digits to form a 4-digit number.
There are five options for the first digit, as we have five digits to choose from. Once we have used one digit, we have four remaining digits to choose from for the second digit. Similarly, for the third digit, we have three remaining choices, and for the fourth digit, we have two remaining choices.
Using the formula for permutations, we multiply these choices together:
Number of ways = 5 * 4 * 3 * 2 = 120
Therefore, there are 120 different 4-digit numbers that can be arranged using the digits 1, 3, 5, 7, and 9 without repetition.