Estimating Addition and Subtraction of Decimals Using Smart Rounding

This lesson teaches how to estimate the addition and subtraction of decimals using smart rounding. It begins with a review of rounding basics, then introduces smart rounding, which involves rounding to familiar numbers for easier calculations. The lesson includes examples with whole numbers and decimals, demonstrating how to apply smart rounding in various scenarios. The concept of relating decimals to fractions and money is also explored to aid understanding.

What is the purpose of smart rounding in calculations?

• To convert numbers into fractions

• To make numbers larger

• To make calculations easier by rounding to familiar numbers

• To make numbers smaller

When using smart rounding, what would 280 round to for easier subtraction?

• 250

• 270

• 300

• 290

How can decimals be related to fractions in smart rounding?

• Decimals are always larger than fractions

• Decimals can be expressed as fractions to simplify rounding

• Fractions are not related to decimals

• Decimals are converted to whole numbers

If you have 0.31, what fraction is it closest to when using smart rounding?

• 3/4

• 1/4

• 1/3

• 1/2

What is the smart rounded result of 8.59 minus 7.30?

• 1.25

• 1.75

• 1.00

• 1.50