Wednesday, September 14, 2011


Today in class we are going to be working on estimating decimal division problems.  Remember, estimate when dividing means to use compatible numbers.  Here is an example:

321.6 / 82.7 =
You would round the 82.7 to 80, which is a number that is close to it that is easy to make a mental math problem out of.  Then you look at the 321.6 and ask yourself, what number is close to 321.6 that 80 can go into evenly.  So you would round the 321.6 to 320.  You would then divide 320/80 and get 4.  I hope this makes more sense for you if you were having a hard time.

Here is one more example:
114.35 / 109.88

Round the 109.88 to 110.
Then round the 114.35  to 110.
110 / 110 = 1, so your estimate would be 1.

On their homework, I want them to show me what they rounded each number to, and then give me the estimated quotient.  DO NOT DIVIDE THE PROBLEM FOR REAL, YOU WILL BE WASTING YOUR TIME!

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