Math Is Fun Forum

megamind

Member

Registered: 2009-12-29

Posts: 2

braingames

Using numbers 1,3,4,6, and basic arithmetic operations (addition, subtraction, multiplication, and division) and parentheses, obtain and expression that evaluates to 24. You may use only these numbers and only these operations. Every number should be used exactly once. Numbers cannot be concatenated, i.e. you cannot use 13 or 146.
Puzzle Obtain 24

A Megamind is lost in the mountains. He is standing on a path, shouting for help. Finally, he sees a local approaching. Megamind knows that the locals can be knights that always tell the truth, or knaves that always lie. He also knows that the path leads to the village of knights in one direction and to the village of knaves in the other. The problems is that the knaves are also hateful of Megaminds, and will stone him if gets to their village. How can Megamind ask one question and determine the right way to go?
puzzle Two villages

A certain type of bacteria double every second. If we put one bacterium in a Petri dish, the dish will fill in 1 minute. How long will it take to fill the dish, if we start with 2 bacteria?
puzzle Bacterium

more on en.braingames.ru

Last edited by megamind (2009-12-30 02:30:01)

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logical puzzles

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: braingames

Hi megamind;

The equation is n* 2^t with n being the number of bacteria you start with and t being time in seconds.

2* 2^t = 2^60 Divide by 2

2^t = 2^59

t = 59 seconds

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

alanklm

Member

Registered: 2009-12-30

Posts: 1

Re: braingames

bobbym, yes, this is right solution. This puzzle is really easy.:)

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: braingames

Hi megamind;

Using numbers 1,3,4,6, and basic arithmetic operations (addition, subtraction, multiplication, and division) and parentheses, obtain and expression that evaluates to 24.

Are you sure these numbers are correct?

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

mathsyperson

Moderator

Registered: 2005-06-22

Posts: 4,900

Re: braingames

I've seen that puzzle before and there is a solution. It's tricksy though.
Happy New Year!

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Why did the vector cross the road?
It wanted to be normal.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: braingames

Hi;

Happy New Year!

I got it!

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.