An easy way to estimate the difference between two numbers is to round each number and then subtract the rounded numbers. 
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Steps to estimate: 1. Round each number
to the greatest place. It may not be the exact difference, but may be close enough. Example: Estimate 1,720  1,195. When rounded to the nearest thousands, 1,720 rounds to 2,000 and 1,195 rounds to 1,000. Now, subtract the smaller number from the greater number.
The estimated difference between 1,720 and 1,195 is 1,000. 

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