I am a positive whole number strictly under 100. When divided by 3, my remainder is 2. When divided by 5, my remainder is 3. When divided by 7, my remainder is 2 again. What number am I?
23
Because dividing by both 3 and 7 gives a remainder of 2, the number must be 2 more than a multiple of 21 (2, 23, 44, 65, 86). Testing these values modulo 5 shows that only 23 leaves a remainder of 3 (since 23 = 4 * 5 + 3).
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: Medium. More like this: Math riddles with answers or try Target 24 for a different kind of puzzle.
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