Repeatition not allowed
How many four-digit numbers can be formed from the numbers 3 5 8 9 if they are not allowed to be repeated?
Correct answer:

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Dr. Math
To determine how many four-digit numbers can be formed from the digits 3, 5, 8, 9 without repeating any digit, we can use the permutation concept. Since the order of digits matters in forming a number, we'll calculate the number of possible arrangements (permutations) of these four digits.
Step-by-Step Solution:
1. First Digit (Thousands place):
- You have 4 choices (3, 5, 8, 9).
2. Second Digit (Hundreds place):
- After choosing the first digit, 3 digits remain.
- So, you have 3 choices.
3. Third Digit (Tens place):
- After choosing the first two digits, 2 digits remain.
- So, you have 2 choices.
4. Fourth Digit (Ones place):
- After choosing the first three digits, only 1 digit remains.
- So, you have 1 choice.
Calculating the Total Number of Four-Digit Numbers:
Multiply the number of choices for each digit position:
Final Answer:
Step-by-Step Solution:
1. First Digit (Thousands place):
- You have 4 choices (3, 5, 8, 9).
2. Second Digit (Hundreds place):
- After choosing the first digit, 3 digits remain.
- So, you have 3 choices.
3. Third Digit (Tens place):
- After choosing the first two digits, 2 digits remain.
- So, you have 2 choices.
4. Fourth Digit (Ones place):
- After choosing the first three digits, only 1 digit remains.
- So, you have 1 choice.
Calculating the Total Number of Four-Digit Numbers:
Multiply the number of choices for each digit position:
4 (choices for first digit) × 3 (choices for second digit) × 2 (choices for third digit) × 1 (choice for fourth digit) = 4 × 3 × 2 × 1 = 24
Final Answer:
24
Tips for related online calculators
See also our permutations calculator.
See also our variations calculator.
Would you like to compute the count of combinations?
See also our variations calculator.
Would you like to compute the count of combinations?
You need to know the following knowledge to solve this word math problem:
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