So What If It’s My Phone Number??

Man, people just do not think sometimes! A friend of mine came to me recently and was incredibly excited because he had been shown the most mind-boggling math trick imaginable. He couldn’t wait to show me. “It’s really cool! You’ll be amazed!” he kept saying. So, here’s what he showed me… try it for yourself:

  1. Get a calculator.
  2. Key in the first three digits of your phone number (NOT the area code)
  3. Multiply by 80
  4. Add 1
  5. Multiply by 250
  6. Add the last 4 digits of your phone number
  7. Add the last 4 digits of your phone number again
  8. Subtract 250
  9. Divide by 2

The answer that you are left with should be your own seven digit phone number. Amazing huh? NO! …I mean, seriously? I thought it was a joke at first. But, no. My friend was seriously amazed by this.

Think about it for a second. You keyed your entire phone number into the equation, so that information is present in there. Then, you basically added a bunch of numbers to your phone number, and then removed those numbers that weren’t your phone number. In the second step, you entered the first three digits of your phone number, and in the sixth step you entered the last four. So, you entered your entire phone number. The rest of the steps are just adding more numbers on top of your phone number and then removing them again.

Yes, it is pretty much that simple. Lets break it down:

In the second step, you entered the first three digits of your phone number. Then in the third step, you multiplied that by 80. So, the author of this “trick” knows that the first three digits of your phone number is the value of X multiplied by 80. Therefore, after step three, we are left with the value of Z. And, the value of Z=X multiplied by 80. So, in order to find the first three digits of your phone number, we simply have to divide Z by 80 and we’ll have it. This could be done in any one of a number of ever more complicated ways later on in the trick in order to fool you into thinking some great, mysterious mathematical phenomena was taking place. We could get you to divide the number by 40, and then divide the resulting number by 2. Or, we could get you to multiply the number by 10, then divide by 400, then multiply that number by 5 and then divide again by 10… etc., etc. But, in it’s simplest terms, all you’re really doing is multiplying the first three digits of your phone number by 80, then dividing that number by 80. However, because of the seemingly complicated process that you have to go through to achieve the result, (add this, subtract that, multiply this) it makes it appear as if some mysterious mathematical phenomena is taking place, when actually, if you just look at it a little, what is happening is you’re just entering your phone number, adding some numbers to that phone number, and then removing the numbers that you added.

Here’s basically the same math trick in a much, much simpler form. See if you’re any less impressed with this one:

  1. Get a calculator
  2. Key in your age
  3. Add 1
  4. subtract 1

What is your answer? Really?!?!?! How did the calculator know how old you are?

I fail to see how anyone over the age of about ten or so would fail to pick up on this in more than a maximum of about a minute or so. Of course, when I told my excited friend (who had been showing this trick to everyone he had come into contact with over the past couple of days) how the trick worked, I thought he was going to cry. I completely took all of the air out of his balloon, and I felt like a heel. Oh well.

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