Whether you are estimating calculations or measurements, a good place to start is to make sure you are in the right ball park.
When you are measuring this means taking the time to think about whether you should estimate your height in inches, feet, yards, or miles. Of course, a worm would estimate their height in inches and a person would use feet or yards.
When you are estimating calculation it is often helpful to note whether your answer is in the tens, hundreds, thousands, etc. You know that 11 x 15 is going to be more than 100 because 10 x 10 is a hundred. If you have the problem 0.5678 + 0.02342 you know it is less than one.
This is especially helpful when you are checking your answer. If you do a simple quick check to figure out what ball park the answer should be in you can often determine if your decimal point is off or if messed up in another way. A quick ball park check can save your grades!
