Number Magic Worksheets: 1089, the 21-Card Trick and the Kruskal Count

Maths that feels like magic: 1089 workouts, a 21-card tracker and Kruskal Count practice rows, every one with a worked answer key.

Who it’s for: Ages 8 to 13.

What’s inside:

- The 1089 trick explained, with the algebra for older magicians

- 1089 workout (12 numbers) and answer key

- Track the 21-card trick, with answers

- The Kruskal Count explained

- Two Kruskal practice pages (6 rows of 20 cards) and answer key

- Credits, licence & sources

Pages: 10 (including cover and credits). Sizes: A4 (210 × 297 mm) and US Letter (8.5 × 11 in), both PDFs in one zip.

Printing: print at 100% / actual size. Inside pages have light backgrounds and print well in black and white; covers are dark, so start from page 2 to save ink.

Every historical and mathematical fact is checked against named sources (Plus Magazine (University of Cambridge), ‘1089 and all that’; Dibyajyoti Deb, paper on the 21-card trick (arXiv:1809.04072); J. C. Lagarias, E. Rains and R. J. Vanderbei, ‘The Kruskal Count’ (arXiv, 2001)), listed on the credits page. The tricks are classic, published methods that need only ordinary cards and coins; no commercial trick is revealed. All drawings and layouts are REALLYBYTE’s own work, starring Useless the eraser as the magician’s (not very helpful) assistant. No photographs are used.

Licence: personal and single-classroom use. Print as many copies as you need for your own family or your own class. Please don’t resell, re-upload or share the files publicly. For school-wide use, email info@reallybyte.com.

Made by REALLYBYTE, the team behind testyourmagic.com. Questions: info@reallybyte.com

This is a digital download: no physical item will be shipped.