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We're going to look at opening safes!
Many have dials on them, and you turn the dials to open them, like in the picture below.
To open the safe, the dial has to be turned so that the number $2$ is next to the arrow, like this:
How much was the dial turned to get the $2$ at the top?
The safe below has a different dial with the numbers $0 - 7$ instead.
How much does the dial have to be turned to get between these two pictures, so that the number $5$ is at the top?
The number that you have to get at the top is often called the "combination" of the safe. These three different safes all start with $0$ at the top. You have to find the amount of turning to get to the combination, shown in each second picture:
Now have a go at these different safes. Remember they would all start with $0$ at the top. How much does each one need to be turned to get to the combinations shown below?
This investigation explores using different shapes as the hands of the clock. What things occur as the the hands move.
During the third hour after midnight the hands on a clock point in the same direction (so one hand is over the top of the other). At what time, to the nearest second, does this happen?
How many times in twelve hours do the hands of a clock form a right angle? Use the interactivity to check your answers.