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Perfect numbers: Difference between revisions
→traditional method: added comments regarding the use of some shortcuts. -- ~~~~
(→{{header|REXX}}: made a version conform more to the original program. -- ~~~~) |
(→traditional method: added comments regarding the use of some shortcuts. -- ~~~~) |
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===traditional method===
Programming note: this traditional method takes advantage of a few shortcuts:
:::* testing only goes up to the (integer) square root of '''X'''
:::* testing bypasses the test of the first and last factors
:::* a ''corresponding factor'' is used when a factor is found
:::* testing is stopped if the sum of the factors exceeds '''X'''
<lang rexx>/*REXX program tests if a number (or a range of numbers) is/are perfect.*/
parse arg low high . /*obtain the specified number(s).*/
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