How many ways can a four digit number be formed with different restrictions?

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The discussion revolves around calculating permutations and combinations for various scenarios involving letters and digits. Participants explore how to arrange letters in words like "MISSISSAUGA" and "BASKETBALL," applying formulas for permutations with repeated elements. They also analyze how to form four-digit numbers under different restrictions, such as using specific digits and ensuring the last digit is odd or even. Clarifications on using the correct formulas, such as n!/(p!q!r!), are provided, alongside discussions on whether digits can be repeated. The conversation emphasizes the importance of understanding permutations versus combinations in solving these problems.
  • #31
Erzeon said:
From the question you wrote, you can't repeat the same number,
ok, i get it...

but this one i don't get it...the last number should be odd because when it's odd, it produces an odd number
 
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  • #32
i mean last digit, odd numbers always have their last digit as an odd number.
 
  • #33
ohh, i know what you mean now... so the answer in 4d would be...still figuring out...lol
 
  • #34
is it 9!/5! or 9x8x7x6 for 4d? since the numbers runs from 0 to 9, but there is only 5 odd numbers, and same thing with 4e?
 

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