Ask questions and get helpful responses.

Math

How many positive 3-digit integers contain only odd digits?

  1. 👍
  2. 👎
  3. 👁
  4. ℹ️
  5. 🚩
  1. first digit has to be 1,3,5,7,9
    as does second, and third.

    number odd numbers= 5*5*5=125
    and curiously, the number of even digits must be 4*5*5 (lead digit cannot be zero)=100
    Now, containing one odd digit.
    4*5*5+5*5*5+4*5*5=325 in two instances, first digit is only of four choices..
    containg two odd digits
    2*5*5*5 + 4*5*5 (second term is first digit is even)= 250+100

    all of those should add to 9*10*10=900
    checking: 350+325+100+125=900

    1. 👍
    2. 👎
    3. ℹ️
    4. 🚩
    👤
    bobpursley
  2. 125

    1. 👍
    2. 👎
    3. ℹ️
    4. 🚩

Respond to this Question

First Name

Your Response

Still need help? You can ask a new question.