Problem 44856. Permutation Via Multiplication

Created by Daniel Bergman

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<div style = "text-align: start; line-height: 20.4333px; min-height: 0px; white-space: normal; color: rgb(0, 0, 0); font-family: Menlo, Monaco, Consolas, monospace; font-style: normal; font-size: 14px; font-weight: 400; text-decoration: rgb(0, 0, 0); white-space: normal; "><div style="block-size: 123px; display: block; min-width: 0px; padding-block-start: 0px; padding-top: 0px; perspective-origin: 407px 61.5px; transform-origin: 407px 61.5px; vertical-align: baseline; "><div style="block-size: 42px; font-family: Helvetica, Arial, sans-serif; line-height: 21px; margin-block-end: 9px; margin-block-start: 2px; margin-bottom: 9px; margin-inline-end: 10px; margin-inline-start: 4px; margin-left: 4px; margin-right: 10px; margin-top: 2px; perspective-origin: 384px 21px; text-align: left; transform-origin: 384px 21px; white-space: pre-wrap; margin-left: 4px; margin-top: 2px; margin-bottom: 9px; margin-right: 10px; "><span style="block-size: auto; display: inline; margin-block-end: 0px; margin-block-start: 0px; margin-bottom: 0px; margin-inline-end: 0px; margin-inline-start: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; perspective-origin: 384px 8px; transform-origin: 384px 8px; unicode-bidi: normal; "><span style="">Given two numbers a and b, determine if the product ab is a permutation of the digits of a. For example, this is always true for a=0. Less trivially, 125874*2=251748.</span></span></div><div style="block-size: 42px; font-family: Helvetica, Arial, sans-serif; line-height: 21px; margin-block-end: 9px; margin-block-start: 2px; margin-bottom: 9px; margin-inline-end: 10px; margin-inline-start: 4px; margin-left: 4px; margin-right: 10px; margin-top: 2px; perspective-origin: 384px 21px; text-align: left; transform-origin: 384px 21px; white-space: pre-wrap; margin-left: 4px; margin-top: 2px; margin-bottom: 9px; margin-right: 10px; "><span style="block-size: auto; display: inline; margin-block-end: 0px; margin-block-start: 0px; margin-bottom: 0px; margin-inline-end: 0px; margin-inline-start: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; perspective-origin: 384px 8px; transform-origin: 384px 8px; unicode-bidi: normal; "><span style="">If the product, ab, has more digits than a, append zeros to the front of a so they have the same number of digits. Thus, for example, 015*7=105 is another example.</span></span></div><div style="block-size: 21px; font-family: Helvetica, Arial, sans-serif; line-height: 21px; margin-block-end: 9px; margin-block-start: 2px; margin-bottom: 9px; margin-inline-end: 10px; margin-inline-start: 4px; margin-left: 4px; margin-right: 10px; margin-top: 2px; perspective-origin: 384px 10.5px; text-align: left; transform-origin: 384px 10.5px; white-space: pre-wrap; margin-left: 4px; margin-top: 2px; margin-bottom: 9px; margin-right: 10px; "><span style="block-size: auto; display: inline; margin-block-end: 0px; margin-block-start: 0px; margin-bottom: 0px; margin-inline-end: 0px; margin-inline-start: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; perspective-origin: 342.5px 8px; transform-origin: 342.5px 8px; unicode-bidi: normal; "><span style="">This problem was inspired by seeing a student simplify 163/326 to 1/2 by cancelling out the digits in common.</span></span></div></div></div>

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Solution Stats

72 Solutions
36 Solvers

Last Solution submitted on Sep 25, 2021

Last 200 Solutions

Problem Comments

Solution Comments

Solution 1740327

1 Comment

1 Comment

Alex on 9 Sep 2020

This returns true for a = 2 and b = 6, but it shouldn't

Solution 1732920

3 Comments

3 Comments

Daniel Bergman on 21 Feb 2019

Any suggestions for improving the test suite would be appreciated!

Tim on 2 Mar 2019

Adding test cases a=105 b=30 and a=111 b=3 should weed out a couple of less-than-general solutions.

Rafael S.T. Vieira on 19 Sep 2020

Add decimal and irrational numbers, but only check if the n-first digits are a permutation of each other.

Problem Recent Solvers36

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digits

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