Calculate with units of length. Will practice doing calculations with units of length. Remember to convert to the same unit before you calculate.

Since $6 \ge 5$, round up the tens digit. $34566 \text{ m} \approx \boxed{34570 \text{ m}}$

Since $6 \ge 5$, round up the hundreds digit. $34566 \text{ m} \approx \boxed{34600 \text{ m}}$

• b) $135 \text{ m}$

Since $5 \ge 5$, round up the tens digit. $135 \text{ m} \approx \boxed{140 \text{ m}}$

Since $3 < 5$, round down. $135 \text{ m} \approx \boxed{100 \text{ m}}$

• c) $2408 \text{ m}$

Since $8 \ge 5$, round up the tens digit. $2408 \text{ m} \approx \boxed{2410 \text{ m}}$

Since $0 < 5$, round down. $2408 \text{ m} \approx \boxed{2400 \text{ m}}$

2. Round off these lengths to the nearest $1000 \text{ m}$.

• a) $3500 \text{ m}$

Since $5 \ge 5$, round up the thousands digit. $3500 \text{ m} \approx \boxed{4000 \text{ m}}$

• b) $34567 \text{ m}$

Since $5 \ge 5$, round up the thousands digit. $34567 \text{ m} \approx \boxed{35000 \text{ m}}$

• c) $1423 \text{ m}$

Since $4 < 5$, round down. $1423 \text{ m} \approx \boxed{1000 \text{ m}}$

3. Do these calculations.

• a) $32456 \text{ m} + 12123 \text{ m}$

$$
32456 \text{ m} + 12123 \text{ m} = \boxed{44579 \text{ m}}
$$

• b) $9 \text{ km} - 7367 \text{ m}$

$$
9000 \text{ m} - 7367 \text{ m} = \boxed{1633 \text{ m}}
$$

• c) $34 \frac{1}{2} \text{ cm} + 12 \text{ cm} + 500 \text{ mm}$

$$
34.5 \text{ cm} + 12 \text{ cm} + 50 \text{ cm} = \boxed{96.5 \text{ cm}}
$$

• d) $\frac{1}{8} \text{ m} + \frac{2}{8} \text{ m}$

$$
\frac{1}{8} \text{ m} + \frac{2}{8} \text{ m} = \frac{1+2}{8} \text{ m} = \boxed{\frac{3}{8} \text{ m}}
$$

4. Do these calculations.

• a) $340 \text{ m} \times 12$

$$
340 \text{ m} \times 12 = \boxed{4080 \text{ m}}
$$

• b) $224 \text{ km} \times 15$

$$
224 \text{ km} \times 15 = \boxed{3360 \text{ km}}
$$

• c) $440 \text{ m} \div 20$

$$
440 \text{ m} \div 20 = \boxed{22 \text{ m}}
$$

• d) $345 \text{ cm} \div 5$

$$
345 \text{ cm} \div 5 = \boxed{69 \text{ cm}}
$$

5. How many quarters of a metre are there in $4 \frac{3}{4} \text{ m}$?

To find how many quarters are in $\frac{19}{4} \text{ m}$, divide $\frac{19}{4}$ by $\frac{1}{4}$.

There are $\boxed{19}$ quarters of a metre.

6. The odometers recorded the following distances from the odometers of her aunts and uncles.
$12374 \text{ km}; 25135 \text{ km}; 60901 \text{ km}; 78345 \text{ km}; 11961 \text{ km}$

• Order the distances the cars have travelled from the shortest to the longest distance.

$$
11961 \text{ km}, 12374 \text{ km}, 25135 \text{ km}, 60901 \text{ km}, 78345 \text{ km}
$$

• Estimate and then calculate the total distance that all the cars have travelled.