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2014 Math Kangaroo

Problem 7

Problem 7 · 2014 Math Kangaroo Easy
Arithmetic & Operations division

Katrin has 38 matches. She uses all of them to make a triangle and a square that share no matches. Each side of the triangle is made of 6 matches. How many matches are in one side of the square?

Show answer
Answer: B — 5
Show hints
Hint 1 of 2
Work out how many matches the triangle uses, then see what is left for the square.
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Hint 2 of 2
Whatever the square gets, split it evenly across its four equal sides.
Show solution
Approach: subtract the triangle's matches, then divide the rest by 4
  1. The triangle has three sides of 6 matches, so it uses 3 × 6 = 18 matches.
  2. That leaves 38 − 18 = 20 matches for the square.
  3. The square's four equal sides share these, so each side has 20 ÷ 4 = 5 matches.
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