Problem 10 · 2025 Math Kangaroo
Easy
Spatial & Visual Reasoning
spatial-reasoning
When Paul sets the number 0000 on his bicycle lock, he sees 8888 at the point marked with an x. To open the lock he must turn the rings so that 2815 shows at the x mark. What number is then next to the arrows?
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Answer: A — 4037
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Hint 1 of 2
Compare the two visible windows: at the arrows you see 0, two rows up at the x you see 8.
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Hint 2 of 2
Each ring is offset by a fixed amount; find the digit at the arrows for each target digit at the x.
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Approach: use the fixed offset between the x-window and the arrow-window
- When the arrows show 0 the x shows 8, so on every ring the arrow digit is 2 more than the x digit (the rows run …,8,9,0,… downward).
- Setting 2,8,1,5 at the x makes the arrows read 2+2, 8+2, 1+2, 5+2 (mod 10) = 4, 0, 3, 7.
- So the arrows show 4037, which is (A).
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