Simply 'having a go' is a great way to make a start on a mathematical problem. Whatever happens, you will have learnt more about the situation and can then tweak your approach. These activities all lend themselves to this 'trial and improvement' way of working.
You have two sets of the digits 0-9. Can you arrange these in the five boxes to make four-digit numbers as close to the target numbers as possible?
Can you use the information to find out which cards I have used?
Can you see how these factor-multiple chains work? Find the chain which contains the smallest possible numbers. How about the largest possible numbers?