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Hanoi Open Mathematics Competition 2011 Senior Question 1

HOMC · Hanoi Open Mathematics Competition 2011 Senior

Question 1

An integer is called “octal” if it is divisible by 8 or if at least one of its digits is 8. How many integers between 1 and 100 are octal?
  1. 22
  2. 24
  3. 27
  4. 30
  5. 33