By Michael Hartley
Mac Oglesby, a retired math teacher, has invented a whole lot of math teaching resources over the years. And it's not just him - he got his family in on the act as well!
Cross-number puzzles are like crossword puzzles - except that instead of word clues, you have number clues. In most cross-number puzzles, you fill the grid with numbers, but the one on this page is different. When Alice Oglesby was 13 years old, she learned about cross-number puzzles, and decided to invent her own. She later had it published in a magazine.
The magazine has long disappeared, but now, I'm thrilled to let you know that it's published again right here on this web page. The download link is below, but first let me tell you what's special about Alice's puzzle. Although each clue gives you a number, you must fill the grid with words! Here's how it works:
- Imagine, for a moment, that the clue for 5 down was "2004 x 19", you'd work this out on your calculator, to get 38076
- Then, you'd turn the calculator upside-down, and you'll see 38076.
- If you look carefully, these upside-down numbers look a bit like letters, and spell the word gLOBE.
- Then, the word 'GLOBE' would be the answer for 5 Down of the cross-number puzzle.
You can read more about Upside-Down Calculator Words elsewhere on this site. For now, without further ado, here's Alice Oglesby's Cross Number Puzzle for you to download. Don't forget to take into account order of operations (PEDMAS or BIMDAS or however you were taught to remember it).
If your kids (or you!) are tickled by this kind of puzzle, why not make some of your own? To help you make your upside-down calculator cross-numbers, I have long almost-complete lists of all the words that you can make by turning a calculator upside-down. You can see the list online or download a two-page printable copy. When you've done, send me a copy! I'd love to see it!