4 Ballpark Estimate

The estimation concept is referred to as making a ballpark estimate. The tricky part has been when the students are given an equation to add but are asked to find a ballpark estimate of the answer instead of the actual answer.

For example, the students might be asked to find the ballpark estimate for this equation.

68+24

On their paper, they would rewrite it like this (along with the answer):

70+20=90

Here are some sample equations that you could use to have them practice.

33+41          75+27          46+8          22+45

The students will also be asked to make a ballpark estimate, compute the answer AND compute the answer of the original equation to compare answers to make sure they are in the ballpark.

Also, don’t forget subtraction.  Try the activity with that operation, too.

After the students are feeling comfortable with single and two-digit ballpark estimates, throw in some three digit numbers to estimate first:  125 would change to 130; 291 would change to 290; etc.