The Ladder …

So we are learning about algebra in Maths and thinking algebraically (is there such a word as this????!) This week, Mary posed a problem for us to think about and work out mathematically …

How many sticks would it take to make a 5 rung ladder?

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If we know how many sticks it takes to make a 5 rung ladder, is there a way we can predict how many sticks we would need for a 13 rung ladder, or a 45 rung ladder??

There was some great team work going to solve this mathematical problem and indeed yes, there is an efficient way to calculate how many sticks you would for 13 or 45 rungs .. or in fact, as many rungs as you like.  Here are some photos of us in action:

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Can you work out the formula?