What's the Trick Behind This Chocolate Brain Teaser?

[amathea]

Found it in a magazine...and as much as I've tried - I cannot solve it. CAn you?

1.First of all, pick the number of times a week that you would like to eat chocolate (try for more than once but less than 10).

2. Multiply this number by 2 (just to be bold).

3. Add 5 (for Sunday).

4. Multiply it by 50 (I'll wait while you get the calculator).

5. If you have already had your birthday this year add 1753, if not, add 1752.

6. Now subtract the four digit year that you were born.

You should have a three digit number. The first digit of this was your original number (how many times you want to eat chocolate each week). The next two numbers are.. YOUR AGE!

 

[KLscilevothma]

Welcome to Physics Forums amathea.
I've posed an explanation here

 

[Doc Al]

Originally posted by amathea
Found it in a magazine...and as much as I've tried - I cannot solve it. CAn you?

Use algebra to see how these number tricks work. If you do steps 1-5, you'll get (using X as your original number):

100X + 2003 (if you had your birthday already)

You should be able to see how the trick works now.