I am a two-digit number whose tens digit is one greater than my units digit. When you square me, my last two digits reproduce me exactly. What number am I?
76
Numbers whose squares end in themselves are automorphic. The two-digit automorphic numbers are 25 (25^2 = 625) and 76 (76^2 = 5,776). For 76, the tens digit (7) is one greater than the units digit (6).
About this riddle
Math riddles hide a calculation inside a short story. Pull out the numbers, work out what is being asked, and watch for a trick such as a unit change.
Difficulty: Hard. More like this: Math riddles with answers or try Target 24 for a different kind of puzzle.
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