A number pattern hides a rule, and finding it is early algebra in disguise. These free printable worksheets show a sequence with one number missing and ask the child to work out the rule and fill the gap.
If they get stuck
The answer key prints on a separate page.
Each sequence follows a single, constant rule: it grows by a fixed step (2, 4, 6, 8), shrinks by a fixed step (30, 25, 20, 15), or grows by a fixed factor (2, 6, 18, 54). The child compares neighboring terms to spot the rule, then applies it to the blank. That habit — look at what changes from one term to the next — is exactly the reasoning that later becomes function rules and expressions.
The blank sits inside the sequence, not at the end, so a child cannot just continue the pattern; they have to run it in both directions to check the missing term fits. Numbers stay friendly so the work is spotting the rule, not the arithmetic.
One question from a sheet like this one, worked a step at a time — with a sentence saying what just happened and why.
Number patterns, step by step