Problem 8 · 2022 Math Kangaroo
Medium
Counting & Probability
careful-counting
All integers from 2 to 2022 which can be written using only the digits 0 and 2 are written in ascending order in a list. Which number is the middle number on that list?
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Answer: B — 220
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Hint 1 of 2
List every number from 2 to 2022 using only the digits 0 and 2.
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Hint 2 of 2
There are 11 such numbers; the middle one is the 6th.
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Approach: list and pick the middle
- The numbers are 2, 20, 22, 200, 202, 220, 222, 2000, 2002, 2020, 2022 — eleven of them.
- The middle (6th) number is 220.
Mark:
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