\displaystyle \text{Total mass}	\displaystyle =	\displaystyle 5+2+2+1+1+1	Add the values
	\displaystyle =	\displaystyle 5 + 4 + 3	Add the 2s and 1s
	\displaystyle =	\displaystyle 12 \text{ kg}	Add the values

Idea summary

When two items are balanced on a scale their weights are equal.

Measure and estimate mass

This video introduces the units of milligrams, grams, and kilograms and discusses the types of objects that would be measured by these units.

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It is most appropriate to use milligrams to measure:

A pencil case

A pig

A small feather

Worked Solution

Create a strategy

Choose the lightest object.

Apply the idea

Milligrams is used to measure very light objects like a small feather. The answer is option C.

Idea summary

The prefixes can help with identifying the size of the units.

milli - for one thousandth of a gram.

kilo - for one thousand of, so a kilogram has 1000 grams.

Milligrams are appropriate to measure tiny very light objects like a small feather and insects.

Grams are appropriate to measure small light objects like a pencil case or cup.

Kilograms are appropriate to measure heavy objects like people and bikes.

selects and uses the appropriate unit and device to measure the masses of objects, and converts between units of mass

7.10 Units of mass