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Knotty Notation

Math brain teasers require computations to solve.


Puzzle ID:#29087
Fun:*** (2.45)
Difficulty:*** (2.49)
Submitted By:kissA****
Corrected By:shenqiang




A single drop of water contains 1.70 quintillion molecules. In the chemistry lab, I'm following a procedure that calls for me to add 30 drops of water to a solution. I must report how many hydrogen atoms I have added to the solution. I must write the answer in scientific notation.

What should I report?

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Mar 13, 2006

WOOHOO! First comment!

I got it pretty easily, but I almost forgot about the amount of Hydrogen in water molecules. Good Teaser!!
Mar 13, 2006

cool cool
Mar 14, 2006

I liked it. My only disagreement would be the number of significant figures. I'm a chemistry major. The answer I have was 1.0*10^20. Only one decimal place. I thought that was the trick. Cool, though.
Mar 16, 2006

I've always been taught to use two digits after the decimal when using scientific notation.
Mar 19, 2006

Too easy, usually figures are taken to 3 significant figures when you have to round.
May 09, 2006

Number of significant figures in result are dependent on input. When multiplying or dividing numbers, find the number with the fewest significant figures, then round the result to that many significant figures.
Feb 04, 2009

There as only two significant figures. Also, the size of the drop can vary, so presumably the number of molecules per drop given is based on the size drop produced by the pipet used to add the drops. If 1.02 x 10^20 was the desired answer then the number of molecules per drop should have been given as 1.70 quintillion.
Feb 04, 2009

I see the teaser was corrected already.
Sep 25, 2013

Fun and simple. I like it!

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