LEARN ALGEBRA!

About a year ago, someone wrote an article in the NYT (I think) about how Algebra was useless. As you might guess, I disagree. Nay, I strongly disagree. Anyway, along comes Suzanne wondering how a little party trick works, and suddenly, here comes Algebra with the solution! I'll first list the trick:

YOUR AGE BY DINER & RESTAURANT MATH

This is pretty neat. Don't cheat by scrolling down first! It takes less than a minute. Work this out as you read; be sure you don't read the bottom until you've worked it out!

1. First of all, pick the number of times a week that you would like to go out to eat. (more than once but less than 10)
2. Multiply this number by 2 (just to be bold)
3. Add 5
4. Multiply it by 50
5. If you have already had your birthday this year add 1756 . If you haven't, add 1755.
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 ( i.e., how many times you want to go out to restaurants in a week.) The next two digits are your age! 2006 is the only year it will ever work!

And now, because this is algebra (which everyone should know) not magic, I will reveal the trick. It's good to do it with a real number so you can see how it works, but because we want to show why it works, we use algebra's favorite number: x.

1. Start with:
x
2. Multiply by 2:
2x
3. Add five:
2x+5
4. Multiply it by 50:
(2x+5)*50
These last two steps are to confuse you so you can't see what's going on. Let's simplify to clear that up:
100x+250
5. Now add either 1756 or 1755. Since we're late in the year, we'll use 1756
100x+250+1756 = 100x + 2006
Hmmm . . . now we can see why this trick will only work this year. This step just makes sure that the number you're adding is the year you had your last birthday in. The trick will work just fine next year, you'll just have to add one more.
6. Subtract the year you were born.
100x + (2006 - 1982) = 100x + 24 = x00 +24 = x24
I put in my year of birth, just for a firm number. Of course, 2006-1982 is my age. The 100x (remember that x is how often you want to eat out) pushes the value x out to the hundreds place where it won't interfere with the calculation of your age. Of course, don't try this trick on anyone 100 years old or older!

Perhaps Suzanne owes me my dollar back?