To subtract the times, we can write it in a vertical algorithm. Make sure to align the hours, colon and minutes.\begin{array}{c} & &5 & : &10 \\ &- &2 & : & 40 \\ \hline & \\ \hline \end{array}

Since 10 minutes is less than 40 minutes, we trade 60 minutes from 5 hours.

So, we have 10+60=70 minutes in the first row and 5 hours becomes 4 hours.\begin{array}{c} & &4 & : &70 \\ &- &2 & : & 40 \\ \hline & \\ \hline \end{array}

Subtracting each column, we have:\begin{array}{c} & &4 & : &70 \\ &- &2 & : & 40 \\ \hline & &2&:&30 \\ \hline \end{array}

The difference is 2 hours and 30 minutes.

Idea summary

We can use subtraction to find the difference between times, but we have to be careful when we need to regroup and remember:

\displaystyle 1 \text{ hour}	\displaystyle =	\displaystyle 60 \text{ minutes}
\displaystyle 1 \text{ minute}	\displaystyle =	\displaystyle 60 \text{ seconds}

Timetables

This video shows you some of the important things that you should consider when looking at public timetables.

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Examples

Example 2

If Charlie catches a train at 4:46 pm from Circular Quay, what time will he arrive at Central?

Station	pm	pm	pm	pm	pm	pm	pm
\text{Museum}	4:21	4:25	4:27	4:31		4:36	4:40
\text{St. James}	4:23		4:29	4:33	4:36		4:42
\text{Circular Quay}	4:27	4:30	4:33	4:37			4:46
\text{Wynyard}	4:29	4:32		4:39	4:41		4:48
\text{Town Hall}	4:32	4:35		4:42			4:51
\text{Central}	4:36	4:39	4:40	4:46	4:46	4:47	4:55

Worked Solution

Create a strategy

Search for the time in the Circular Quay row. Then go down the column to the Central row to find the train's arrival time.

Apply the idea

Charlie will arrive at Central at 4:55 pm.

Idea summary

Every timetable is different. Before you start answering questions on a timetable you haven't seen before, look at all the information, such as:

9.08 Timetables

Ideas

Are you ready?

Examples

Example 1

Timetables

Examples

Example 2

Outcomes

ACMMG139

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