Grab a *calculator* (You won't be able to do this one in your head)2. Key in the first four digits of your *phone number* (NOT the area code-if your *number* is 01.. Adapted for *Australian* conditions, hehe (hopefully correctly) from

Step four: Have them type the first three digits of their *phone number* (not including the area code, or first four digits if you're from the UK) into the *calculator* .

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In this math *trick*, you get your friend to do a sequence of arithmetic steps.. Enter the *number* 7; Multiply by the month of your birth; Subtract 1; Multiply by 13. If you are in Europe or *Australia*, you probably want February 29 to look like 29.02,

In this math *trick*, you get your friend to do a sequence of arithmetic steps. Then you divine their birthday, or another secret *number*, almost magically from the answer.. Give your friend a *calculator*, and ask them to follow these simple steps :. Of course, if you are in Europe or Asia or *Australia*, you'll want the 29th February .

GS1 Check Digit *Calculator* can *calculate* the last digit of a barcode *number*, making sure the barcode is correctly composed. *Calculate* a check digit.