askvity

How many 9-digit numbers with different digits can be formed?

Published in Combinatorics 2 mins read

There are 3,265,920 possible 9-digit numbers that can be formed using different digits.

Here's how we arrive at that answer:

  • Understanding the Constraints: We need to form a 9-digit number using distinct digits (0-9), meaning no digit can be repeated. The first digit cannot be zero.

  • Breaking Down the Problem: We consider each digit place value individually.

    • First Digit: The first digit can be any number from 1 to 9. So there are 9 choices.

    • Second Digit: Now we have used one digit. We can use 0, but not the digit chosen for the first place. This gives us 9 choices again.

    • Third Digit: We've used two digits. So we have 8 remaining choices.

    • Fourth Digit: We've used three digits. So we have 7 remaining choices.

    • Fifth Digit: We've used four digits. So we have 6 remaining choices.

    • Sixth Digit: We've used five digits. So we have 5 remaining choices.

    • Seventh Digit: We've used six digits. So we have 4 remaining choices.

    • Eighth Digit: We've used seven digits. So we have 3 remaining choices.

    • Ninth Digit: We've used eight digits. So we have 2 remaining choices.

  • Calculation: To find the total number of possible 9-digit numbers, we multiply the number of choices for each digit place:

    9 9 8 7 6 5 4 3 2 = 3,265,920

Therefore, 3,265,920 different 9-digit numbers can be formed using different digits.

Related Articles