Post a New Question

Math

posted by .

There are 900 three-digit integers. The number of three-digit integers having at least one repeated digit is also a three-digit number. If that number is represented by abc where each letter is a digit compute a-b+c.

  • Math -

    Already answered.
    math - MathMate, Saturday, May 28, 2011 at 11:00pm
    Here we have 10 digits, of which the first one cannot be zero.
    If the three digits are distinct, there are 9 choices for the first digit, still 9 (including zero) for the second, and 8 for the third.
    So 9*9*8=648 numbers.
    There are therefore 900-648=252 numbers which have at least one repeated digit.
    So a=2, b=5, c=2, and a-b+c=2-5+2=-1

Answer This Question

First Name
School Subject
Your Answer

Related Questions

More Related Questions

Post a New Question