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Write down the number $4$, four times.
Put operation symbols between them so that you have a calculation.
So you might think of writing $4 \times 4 \times 4 - 4 = 60$
Now, can you redo this so that you get $15$, $16$ and $17$ for your answers?
Need more of a challenge? Try getting answers all the way from $0$ through to $10$.
Place four pebbles on the sand in the form of a square. Keep adding as few pebbles as necessary to double the area. How many extra pebbles are added each time?
Investigate the different shaped bracelets you could make from 18 different spherical beads. How do they compare if you use 24 beads?
How many different shaped boxes can you design for 36 sweets in one layer? Can you arrange the sweets so that no sweets of the same colour are next to each other in any direction?