> For the complete documentation index, see [llms.txt](https://trizen.gitbook.io/perl6-rosettacode/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://trizen.gitbook.io/perl6-rosettacode/programming_tasks/p/positive_decimal_integers_with_the_digit_1_occurring_exactly_twice.md).

# Positive decimal integers with the digit 1 occurring exactly twice

```perl
say display 10, '%3d', ^1000 .grep: { .comb.Bag{'1'} == 2 };

sub display {
    cache $^c;
    "{+$c} matching:\n" ~ $c.batch($^a)».fmt($^b).join: "\n"
}
```

#### Output:

```
27 matching:
 11 101 110 112 113 114 115 116 117 118
119 121 131 141 151 161 171 181 191 211
311 411 511 611 711 811 911
```