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177 problems, every one written from scratch, every wrong answer carrying the mistake that produces it. 708 explanations in all.
14 problemsClear all filters
How many two-digit numbers have digits that add up to 8?
How many 2 by 2 squares fit on a 4 by 4 board, if they must line up with the grid?
How many of the numbers from 1 to 20 are not multiples of 3?
A cafe offers 3 main courses and 2 puddings. How many different two-course meals can be ordered?
A coin is tossed three times. In how many of the possible outcomes are there exactly two heads?