Doubling and Halving Challenges

Something 'fishy' about this!

It isn't often that it is good to get questions incorrect but carrying out an investigation into which numbers double and halve using these triangular grids has given us just that opportunity.
As you can see in this example, starting with the number 6 works here. As well as working up the grid we also worked down the grid.
Doing this we found out that numbers such as 18, 30, 42 do not give us an answer with a whole number (the rule was we couldn't get to a fraction or a decimal number).
Working on questions like this where we are uncertain about the outcome really helps us develop our mathematical understanding and is another way of helping us respond positively to challenges.