Check differences first
Subtract each term from the next. If the difference is constant, a repeated addition or subtraction rule may fit.
Number Sequence Practice: Find a Rule and Check Two More Terms
A guess fits once.
A rule fits every step.
Look at the whole sequence before choosing a rule. Six short puzzles ask you to test a pattern, then use it to predict two more terms.
Try the first puzzle ↓No sign-up · No tracking scripts · Your inputs stay in this page
Check each transition.
Each puzzle has one intended answer among three rules. No timer, no score, and explanations are always available.
Nothing is saved or sent. Reloading restores the example.
EXPLORE THE RESULT
Puzzle 1 of 6
For 3, 7, 11, 15, the displayed differences are +4, +4 and +4. Among the offered rules, adding 4 fits each step and predicts 19, 23.
Then test multiplication or alternation
A constant ratio can suggest multiplication. Alternating differences can suggest two steps that repeat in order.
Do not claim a finite list proves a unique rule
Many constructed rules can fit a short list. Each puzzle here has one intended rule among its displayed choices, not the only mathematically possible continuation.
Cognilo: Brain Training Games
Keep the puzzle habit varied with Cognilo
Cognilo's Daily 5 includes short puzzles across memory, focus, logic, numbers, spatial and language categories. Rule Chain uses sequences, and each round includes a strategy tip. The free tier includes daily play; Pro is optional.
Explore Cognilo on the App Store ↗This separate lab is recreational practice. It does not measure IQ, diagnose attention problems or prove any improvement in general cognitive ability.
App details checked against the official App Store listing on November 4, 2026. Check current availability and purchase terms there.
Questions before you continue
Can more than one rule fit a number sequence?
Yes. A finite list can have many continuations. This activity asks you to choose among three stated rules.
What happens if I pick the wrong rule?
You get a prompt to check every transition and can try again or reveal the explanation.
Is there a timer or score?
No. Work at your own pace and use the explanation whenever you want.
Useful for someone else?
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