I have made a lot of toilet roll covers. Some were for our Toilet Roll Covers book; some have been of a more mathematical nature.

I have often looked at using Fibonacci numbers on a cover but the numbers don’t really make an interesting design. Then I was reminded of Lucas numbers.

Lucas numbers (or Lucas Series) works in the same way as Fibonacci numbers. Two numbers are added together to give the next term in the series.

• Fibonacci begins 0, 1, 1, 2, 3 … (or is sometimes written as 1, 1, 2, 3 …)
• Lucas begins 2, 1, 3, 4 …

The Lucas Series fits nicely on a toilet roll. The numbers of ridges round the cylinder are 2, 1, 3, 4, 7, 11, 18, 29 (Total 75). The ridges on the top are 2, 1, 3, 4. The bottom edge has 2 ridges.

This is very easy to knit, on straight needles. It begins with a provisional cast-on and the seam is closed with a 3-needle bind-off.

It uses less than 40 metres DK of each colour. You could double the height if you wanted to fit two rolls inside.

The ebook contains patterns for eleven knit and crochet toilet roll covers based on mathematical concepts. It also has a section that will help you to design your own covers.

The patterns are not available individually but if you want just one I can supply it in return for a small donation to my favourite charity.