Turn on the calculator and perform the following mathematical processes in front of your friends. Make sure that they see you performing the math on the calculator and the results at each step.
1. Ask them for the first three numbers of their seven-digit phone number (not the area code).
2. Multiply the number by 80.
3. Add 1.
4. Multiply by 250.
5. Ask them for the last four digits of their phone number and add it.
6. Add the last four digits of their phone number again.
7. Subtract 250.
8. Divide by 2.
9. Show your spectators the final number, which amazingly, will be their seven-digit telephone number.
