The Right Ball Park

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!

What is Estimating

I like to think of estimating as the pickel in the middle. On the one hand you can guess; estimating is not guessing. If I ask you what 11 x 13 is and you pull a number out of the hat that is guessing.

One the other hand you can do the calculation; estimating is not being precise. If I ask you the same question and you calculate the answer that is not estimating.

Estimating is an educated guess. It is using what you know to get close to the answer. If you say, "11 x 13 is a little more than 10 x 13 = 130, so I estimate the answer is 140," that is estimating.

Place Value

Place value is a vague concept for many students. Often we think of 10 as ten individual marbles or 10 individual cookies but when we look more at place value it shifts how we think about numbers. Place value has to do with groups. The tens position tells us how many groups of 10 there are, so the number 10 means one group of 10 and zero individual ones.

All of the place values are based on this group concept. When there gets to be too many tens we then group in terms of 100s and that place value is called the hundreds place. So the number 234 is two groups of 100, three groups of 10 and four individual ones. If you understand place value it will help you with many other math topics.