Function machines: in goes a number, out comes another
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What you will learn
By the end, you can find the rule of a function machine and say what number comes out.
A magic box eats a number and changes it by a secret rule. Drop in a 3, a 7 comes out. Drop in a 4, an 8 comes out. Work out the rule and you can predict any answer. Mathematicians call this box a function machine.
Read the explanation
A function machine takes a number in, follows one rule, and gives a number out. To find the rule, look at what changed between the in and the out. If 3 becomes 7 and 4 becomes 8, the rule is “add 4”. Once you know the rule, you can apply it to any number that goes in.
- Compare in and out to find the change.
- The change is the rule.
- Apply the rule to any new number that goes in.