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Puzzles
121
Source:
Mathematical Circus
by Martin Gardner
Find a number base other than 10 in which 121 is a perfect square.
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This is true for any base larger than 2. This is because:
$$121_n = 1+2n+n^2$$ $$=(n+1)^1$$
Extension
Which other base 10 square numbers are always square in high enough bases?
Tags:
numbers
,
bases
If you enjoyed this puzzle, check out
Sunday Afternoon Maths XLIV
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ave
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the only crossnumber
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cryptic crossnumbers
chalkdust crossnumber
expansions
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means
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colouring
odd numbers
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speed
crossnumbers
digital clocks
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division
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proportion
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doubling
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