Math Brain Teasers

Finally! I found my favorite book. If I had to choose one book from all my books I would definetly take this one. This is just brilliant.

The publisher says “Let The Brainwaves Center™ be your personal mind-trainer A 90-day mental exercise program that is actually fun! Plus 92 insider’s tips to improve real-world performance.”

And this is serious! They are not lying. This book is so much fun! I´ve never seen a more entertaining way to improve your brain power! I love it!

PS: It´s crammed with math brain teasers.

Now this one of those math brain teasers that are a really a hard nut to crack. So I have to warn you: Only proceed reading if you dare to…

Let´s do it:

You have two very hungry termites and two sticks of wood. One stick of wood is 12 inches long and the other is 16 inches long. One termite can eat sticks at the rate of 1 inch every 3 minutes. The other termite can eat 1 inch in 4 minutes. How would you use the termites and sticks to measure 61 minutes?

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Start the slow termite eating the longer stick. It will take the slow termite 16 minutes to eat the 4 inches that will make the sticks the same size. When the sticks are the same size, start the fast termite on the other stick. This termite will finish his 12 inch stick in 36 minutes. That’s 52 minutes elapsed so far and the slow termite still has 3 inches left on his stick. Remove the slow termite and let the fast termite finish off the 3 inches in 9 minutes for a total of 61 minutes.

James: “Do you know, when the Jacksons married 18 years ago, Mr. Jackson was three times as old as his wife, and today he is just twice as old as she?”

Shirley: “Then how old was Mrs. Jackson on the wedding day?”

Can you answer Shirley’s question?

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X=Mr.Jackson’s age 18 years ago
W=Mrs.Jackson’s age 18 years ago
X=3W

X+18=2(W+18)
X+18=2W+36

X=2W+18
-(X=3W)
0=-W+18
W=18

W=18 X=54

If a hen and a half lay an egg and a half in a day and a half, how many eggs will six hens lay in seven days?

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(1.5 hens)*(1.5 days)=(1.5 eggs)
2.25(hens*days)=(1.5 egg)
(1 hen*1 day)=(2/3) egg
6*7*((1hen*1day)=(2/3) egg)
42(hens*days)=28 eggs
They’ll lay 28 eggs.

I´m always happy when I find math brain teasers like this. Just pass me a mail if you like them too.

Complete the right side of the following equation, subject to the rules below:

24=

Rules:

1. Use the number “1″ once and the number “5″ three times, i.e., use only these four digits, and use all of them—1, 5, 5, and 5.
2. Use any combination of parentheses and the operations of addition, subtraction, multiplication, and division.

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(5 – 1/5) x 5

This is one of the math brain teasers I recently found  on the net.

I hope somebody will read this some day. Maybe there is somebody out there who shares my love for fiddly math brain teasers. In the following posts I´m going to put up some of my favorite math brain teasers.

I hope you´ll enjoy them.