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Basic Math/Basic Addition

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Question
Hi, i have a job interview coming up soon, and part of it is to take a math test. Basically all you need to do is add, or subtract together any number of prices. I need to know the quickest and most efficient way to do this mentally, thank you.

Answer
Hello,

There is no quick answer, but I can refer you to websites that can help.
What I do is mentally round numbers just to get an approximate result -- which
is usually adequate for most purposes.  For example:
$1.29 + $5.19 + $3.99 + 15.25 + $48.39...round as follows...
$1 + $5 + $4 + $15 + $49 (rounded-up since I rounded the others down by about 30, 20
and 50 cents...so rounding up by about 60 cents almost makes up for the other round-downs).
Now these numbers are easy to mentally add: $74 (with the true answer being $74.11...see?

Anyhow, here are some links that offer more strategies:
http://www.teachingintheearlyyears.com/2011/10/mental-math-addition-strategies.h
http://www.youtube.com/watch?v=wZmlDfRekpU
http://olc.spsd.sk.ca/de/math1-3/p-mentalmath.html
http://www.origoeducation.com/mental-computation-strategies-addition/?mageloc=US
http://ianthompson.pi.dsl.pipex.com/index_files/mental%20calculation%20strategie

Good luck!

Abe

Basic Math

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Abe Mantell

Expertise

Hello, I am a college professor of mathematics and regularly teach all levels from elementary mathematics through differential equations, and would be happy to assist anyone with such questions!

Experience

Over 15 years teaching at the college level.

Organizations belong to
NCTM, NYSMATYC, AMATYC, MAA, NYSUT, AFT.

Education/Credentials
B.S. in Mathematics from Rensselaer Polytechnic Institute
M.S. (and A.B.D.) in Applied Mathematics from SUNY @ Stony Brook

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