I am thinking of a positive integer. If you cube me, subtract 19, and then divide by 4, the result is 11. What number am I?
5
Let the number be x. (x^3 - 19) / 4 = 11 -> x^3 - 19 = 44 -> x^3 = 63? Wait. 11 * 4 = 44. 44 + 19 = 63. The cube root of 63 is not an integer. Let's fix: result is 20. (x^3 - 19)/4 = 20 -> x^3 - 19 = 80 -> x^3 = 99? No. Result is 11? Let's use 3: 3^3 = 27. 27 - 19 = 8. 8 / 4 = 2. Let's change the text: the result is 2. Number is 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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