A math trick

1. Grab a calculator and a sheet of paper.
2. Key in the first 4 digits of your phone number. Multiply this by 40.
3. Add 1 and multiply by 250. Divide by 10.
   
4. Add your age at your last birthday. Multiply this by 15.
   
5. Draw a square on the sheet of paper and divide it into four smaller squares.
   
6. Draw a circle on a sheet of paper and write the first 3 digits of the number from the calculator inside the circle.
   
7. Enter the year you were born on the calculator and then subtract the number you've written in the circle.
8. Write the first four digits from the number that appears on the calculator into the 4 squares, one in each square, in any order.
9. Add up the two columns of numbers in the squares, and then add together the two totals. Enter that number into the calculator.
   
10. I'm just making this up as I go along, you know.
11. Add 150. Write that number on the back of your hand.
    
12. I bet you wish you'd read this far down before you started pissing about with calculators and pieces of paper.
13. Draw the number 22 on your forehead.
    
14. Take away 15. Divide by the number from step 7.
15. Subtract 10.
16. Take the top half of the number you have and multiply this by the number from step 1.
17. Write this answer on the sheet of paper.
18. Subtract 15. Divide by 10.
19. Take the first digit of this number and count down that many lines.
20. Count the number of letters in the first word of that sentence.
21. Add this to your result.
22. Recognise the number?
    

Uncanny huh!? I'd be interested in knowing how it works!