Problem 9 · 2016 Math Kangaroo
Easy
Number Theory
digit-sum
If you add up the digits of the year 2016 (2 + 0 + 1 + 6), the result is 9. What is the next year after 2016 for which the sum of the digits is 9 again?
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Answer: B — 2025
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Hint 1 of 2
The next year must be after 2016 and have digits adding to 9.
Still stuck? Show hint 2 →
Hint 2 of 2
Try years just after 2016 and add their digits.
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Approach: check years after 2016 for digit sum 9
- Add the digits of each year right after 2016: 2017 gives 10, 2018 gives 11, and they keep climbing, so none of 2017–2024 lands back on 9.
- Keep going to 2025: 2 + 0 + 2 + 5 = 9.
- So the next such year is 2025, choice B.
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