2022 AMC 10 B

Complete problem set with solutions and individual problem pages

Problem 4 Easy

How many three-digit positive integers have an odd number of even digits?

  • A.

    150

  • B.

    250

  • C.

    350

  • D.

    450

  • E.

    550

Answer:D

There are 5\times 5\times 5\times 2 \text{ (odd/even/odd and odd/odd/even) }+4\times 5\times 5 \text{ (even/odd/odd)}=350 ways to let the number have one even digit, while 4 \times 5\times 5=100 ways to let the number have three even digits. So the answer is 350+100=450 such numbers.

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