Task and description from: @maths26772621
This could be extended in many different directions depending on the starting and target values. These could easily be set by the teacher or as I have done allow the pupils to select and in fact, I eventually had them create questions that their partner then had to solve which resulted in some tough questions. Quite quickly tweaks needed to be made like no multiplication by 1 but I wanted them to discover this “cheat”. If the instructions potentially pose an issue, then you could set it up the way I have in the example but have them try to fill in the blanks for a few attempts?
Starting Points Maths 
First step should be 0.05×2=0.1.Thanks for the idea.
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