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# Treebeard's Stumper Answer8 May 98

A Calculator Trick

Today is the 15th Dunn Middle School Science Fair! So here's a calculator trick that uses your age as well as your address (or zip code).
 1) Enter your address 93441 2) Double it 186882 3) Add 5 186887 4) Multiply by 50 9344350 5) Add your age (here 15) 9344365 6) Add days in a year (365) 9344730 7) Subtract 615 9344115
There's your address and age again, combined as one number! Why does this work?

50(2x+5)+y+365-615 = 100x+y.

Note: Here are all the steps as algebra:
 1) Enter your address (here x) x 2) Double it 2x 3) Add 5 2x+5 4) Multiply by 50 50(2x+5) 5) Add your age (here y) 50(2x+5)+y 6) Add days in a year (365) 50(2x+5)+y+365 7) Subtract 615 50(2x+5)+y+365-615 8) Simplify 100x+250+y+365-615 100x+y+615-615 100x+y

It's not hard to make up your own mathemagic tricks like this!

The Dunn Middle School Science Fair was a great success! We'll soon post abstracts of our projects on the DMS Homepage. My project was a Windows program for composing MIDI Drum tracks. It's available for download from Treebeard's Basic Vault.

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