Thursday, June 24, 2010

Dating Math Puzzle

Image by BostonBill

On a hot date, young gentleman was trying to guess the age of his new acquaintance. She was flirting and refusing to reveal it. Then he offered her the following game:
He asked her to take the number of the month in which she was born (January - 1, February - 2, etc).
Double it.
Add 4.
Multiply by 50.
Add her age.
Subtract 200.
And tell him the answer.

After that he looked at her very suspiciously and quickly drove her back to her house. Why?

Submit your answer on our Family Puzzle Marathon Be first to solve three puzzles and get a prize!


Kim said...

Using his little math trick, he can determine both her age and the month she was born.

Here's how:

The equation that explains what he did is:
x is the month she was born
y is her age

(2x+4)* 50 + y - 200
= 100x + 200 + y - 200
= 100x + y

So her age is determined by the tens and ones digits, and her month of birth is determined by the thousands and hundreds digit

(e.g., if she was born in February and her age is 30, her answer will be 230)

Unknown said...

He figured out that she was a minor.

Maria said...

You are both right - gentleman played a math trick and, as Kim beautifully explained,figured out his date's year and month of birth. Most likely she was too young for his plans. Another puzzle point for Kim!
In an alternative scenario, the date made a mistake in her math that resulted in her being way too old.

Donna said...

([(mox2)+4]x50)+AGE= mox100+200+AGE.....once you subtract the 200 out of this equation, you end up with a number either in the hundreds with the hundreds digit being the month in which you are born, and the last 2 digits being your age, or a number in the thousands (if you were born in October or later) again with the last 2 digits being your age. She was obviously jail-bait, and he was wise to take her home. :)

Maria said...

Donna - welcome to the Puzzle Marathon! You are swift and smart and right. Unfortunately, only the first one who solves each puzzle correctly gets a puzzle point. Please check every Friday for new puzzles posted to get a chance to crack them first.

Donna said...

Sorry, Maria.....I didn't realize new puzzles are posted every Friday and I must solve them first to get points. Thanks for the info....I was just trying to answer them without looking at what anyone else said to challenge myself. I love this stuff....keep em coming!

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