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2020 Math Kangaroo

Problem 1

Problem 1 · 2020 Math Kangaroo Medium
Arithmetic & Operations order-of-operations

When the results of the following additions are written in descending order, what sum will be in the middle?

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Answer: C — 1 + 23 + 45
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Hint 1 of 2
Each option glues some digits together before adding — work out the five totals first.
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Hint 2 of 2
Once you have the five sums, you only need the one that lands in the middle when ordered.
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Approach: evaluate each sum, then find the median of the five values
  1. The five totals are 348, 60, 69, 51 and 240.
  2. Put them in descending order: 348, 240, 69, 60, 51.
  3. The middle (third) value is 69, which comes from choice C.
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