Perfect numbers: Difference between revisions
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(→traditional method: added comments regarding the use of some shortcuts. -- ~~~~) |
m (→optimized using digital root: added a factoid. -- ~~~~) |
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===optimized using digital root=== |
===optimized using digital root=== |
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This REXX version makes use of the fact that all known perfect numbers > 6 have a ''digital root'' of '''1'''. |
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<lang rexx>/*REXX program tests if a number (or a range of numbers) is/are perfect.*/ |
<lang rexx>/*REXX program tests if a number (or a range of numbers) is/are perfect.*/ |
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parse arg low high . /*obtain the specified number(s).*/ |
parse arg low high . /*obtain the specified number(s).*/ |
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