Permutable and

reversible

Weekly challenge 176 — 1 August 2022

Week 176 - 1 Aug 2022

Task 2

Write a script to find out all `Reversible Numbers`

below `100`

.
A number is said to be a reversible if sum of the number and its reverse have only odd digits.

Example 1: 36 is reversible number as 36 + 63 = 99 ie all digits are odd.Example 2: 17 is not reversible as 17 + 71 = 88, none of the digits is odd.

We are looking for a number written as AB such that AB + BA has only odd digits.

The sum is 10A + B + 10B + A, which is 11 (A + B). No single digit number will qualify, so all we need to do is look from 10 to 99 checking that 11 (A + B) doesn't contain [02468].

#!/usr/bin/perl # Peter Campbell Smith - 2022-08-01 # PWC 176 task 2 use v5.28; use utf8; use warnings; my ($j, $result); # loop over all 2-digit numbers for $j (10 .. 99) { $j =~ m|(\d)(\d)|; # check sum of digits * 11 $result .= "$j, " unless (11 * ($1 + $2)) =~ m|[02468]|; } # output $result = substr($result, 0, -2); say qq[\nOutput:]; say $1 while $result =~ m|(.{0,36})|g;

```
Output:
10, 12, 14, 16, 18, 21, 23, 25, 27,
30, 32, 34, 36, 41, 43, 45, 50, 52,
54, 61, 63, 70, 72, 81, 90
```

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