# When Big Gets Smaller

*Keywords:*

AO elaboration and other teaching resources

Solve multiplication and division problems that involve fractions.

Number Framework Stage 8

#### Using Number Properties

Problem: “Nara buys 0.345 kilograms of chocolates, which costs $9.78 per kilogram. Work out the approximate cost. Is the answer less than or more than $9.78?”

*(Possible answer: 0.345 *x *9.78 *≈ *3 tenths of 10 = 3. So the answer is less than $9.78.)*

Use the calculator to find the cost of the chocolates and round sensibly.)

*(Answer: 0.345 *x *9.78 = 3.3741 = $3.37 to the nearest cent.)*

Examples: Worksheet (Material Master 8–15).

#### Understanding Number Properties:

How will you work out whether the answers to problems like 56.8 x 1.088 or 0.000123 x 567 get bigger or smaller?

#### Understanding Number Properties:

z x y is always smaller than z when y is ... (Answer: less than 1).

z x y is always bigger than z when y is ... (Answer: greater than 1).