Track / Stage 4 / 7 of 340 #267 of 1964

8. How many two-digit squares differ by 1 from a multiple of 10 ?
A 1
B 2
C 3
D 4
E 5

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Official solution

8. B The two-digit squares are $16,25,36,49,64$ and 81 . Of these, only 49 and 81 differ by 1 from a multiple of 10 .

Source: NuminaMath-1.5, licensed Apache-2.0. Statement and solution reproduced as published; topic, difficulty and ordering added by this site.