Track / Stage 4 / 12 of 340 #272 of 1964

Problem 272

AMC 12 late, AIME early

Number theory Difficulty 4.4 Find the answer

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

Your answer

Multiple choice: answer with the letter of the option you want.

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 reproduced verbatim; metadata (topic, difficulty, ordering) added by this project.