6.5 DISCOVER THE MATHEMAGICAL FORMULA in-depth path

The formula

Phone number without area code: 12345678

Name the first four digits x and the last four digits y

1. Enter the first four digits 

x

 

2. Multiply your answer by 80

80x

 

3. Add 1

80x + 1 

 

4. Multiply your answer by 250 

250(80x + 1) 

= 20000x + 250 

 

5. Add the last four digits 

20000x + 250 + y 

 

6. Again, add the last four digits of your phone number

20000x + 250 + y + y 

= 20000x + 250 + 2y 

 

7. Subtract 250 

20000x + 2y 

 

8. Divide your answer by 2

(20000x + 2y) : 2 

= 10000x + y 

 

9. The mathemagical formula for the phonenumber is

Phone number = 10000x + y 

where x is the first four digits of your phone number 

and y is the last four digits of your phone number