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PrintSouth African Mathematics Olympiad
South Africa counting and probability
Problem
How many of the integers between and are multiples of or ? (A) (B) (C) (D) (E)
Solution
E Between (and including) and there are multiples of ; between and there are multiples of . Between and there are multiples of . The number we seek is
Final answer
E
Techniques
Inclusion-exclusionOther