Estimating Middle Years Examples

       Estimation 180¹

Multiplying whole numbers, multiplying fractions, multiplying decimals

Estimating Fractions ¾  + ½ will that be more than 1 or less than 1?

If you estimated the answer to ⅓ x ½ would it be greater than one or less than one?

Would the answer to ½ x ⅓ be greater than one or less than one?

Estimation should be an ongoing strategy that is used as students approach proficiency in their operations with numbers. For example, when multiplying two values, number sense would lead a student to estimate a larger product that is proportional to the values of the two factors. Mental math strategies to approximate a reasonable answer may be applied, such as using front-end rounding in the earlier stages of readiness, to using compensation or compatible numbers as a more refined strategy.

Ex: 4 672 x 5 309 = 24 803 648

A student beginning to develop estimation strategies may choose front-end rounding as a starting point and multiply 4 000 x 5 000 = 20 000 000. As number sense develops, a realization that each of these numbers is approximately 300 away from the nearest thousand will occur. Using compensation as a strategy, then, would achieve a much more accurate estimate that is closer to the actual product (5 000 x 5 000 = 25 000 000).

¹Math Lessons that Build Number Sense. [online] Available at: <https://estimation180.com/> [Accessed 19 August 2021].