Drexel dragonThe Math ForumDonate to the Math Forum

Ask Dr. Math - Questions and Answers from our Archives
_____________________________________________
Associated Topics || Dr. Math Home || Search Dr. Math
_____________________________________________

Front End Estimation of Addition Problems

Date: 09/06/2005 at 19:53:51
From: Kristin
Subject: front end estimation

Could you give me an example problem so I can learn how to do front 
end estimation?  Here's an example:

  436     400
+ 517   + 500
_____________    
          900

Is this correct?



Date: 09/06/2005 at 22:59:14
From: Doctor Peterson
Subject: Re: front end estimation

Hi, Kristin.

Yes, that's correct.

The main idea of FEE is that the "front-end" digits (the ones on the
left) are the most important because their place value is the 
greatest.  So if you want to estimate by ignoring most digits and
using as few as possible, you will do best if you use only the "front
end", and replace everything else by zero, as you did.

There are other tricks for getting a better estimate which you will be
learning later--these may be called "adjustments", or may be taught as 
"rounding".  What you've learned should be enough for the moment, but 
you will do well by thinking after doing each problem, "How far off do 
I expect my answer to be?  Will the exact answer be more or less than 
what I estimated?" 

Then do the exact addition and see if you were right.  Do that enough,
and you'll be a good estimator!

So make up your own problems, and then check your answers that way. 
That will be worth more than any sample problems I could give you. 
You may run across some tricky cases; if you don't understand why some
of your estimates are farther off than you expected, write back and
tell me what you found, and we can discuss it.


- Doctor Peterson, The Math Forum
  http://mathforum.org/dr.math/ 
Associated Topics:
Elementary Number Sense/About Numbers
Elementary Place Value
Middle School Number Sense/About Numbers

Search the Dr. Math Library:


Find items containing (put spaces between keywords):
 
Click only once for faster results:

[ Choose "whole words" when searching for a word like age.]

all keywords, in any order at least one, that exact phrase
parts of words whole words

Submit your own question to Dr. Math

[Privacy Policy] [Terms of Use]

_____________________________________
Math Forum Home || Math Library || Quick Reference || Math Forum Search
_____________________________________

Ask Dr. MathTM
© 1994-2013 The Math Forum
http://mathforum.org/dr.math/