Input Output Games Online
Free input output games online. No login required.
- 100% Free
- Works on phones and tablets
- Instant feedback
Play the Function Machine Game
A secret machine follows one math rule. Tap a test number, watch the output, then pick the rule that works every time.
What Is an Input Output Game?
An input output game is a math puzzle built on one simple idea: a number goes in, a machine follows a secret rule, and a new number comes out. Your job is to test numbers, watch the outputs, and find the rule the machine is hiding. The machine can hide any rule: addition, subtraction, multiplication, division, or even two steps at once.
Try this example. Put 3 in and 7 comes out. The rule might be "add 4". Now put 5 in. If 9 comes out, "add 4" still works. Two matches are a good sign, but a careful thinker checks every pair before choosing. Testing and checking like this is the same idea behind math functions and algebra: one number goes in, one number comes out, and the rule always behaves the same way.
What Is an Input?
The input is the number that goes into the machine first. In the pair "3 in, 7 out", the input is 3. You pick the input when you test, so choose numbers that help you compare quickly. A good tester tries different inputs, not the same one twice.
What Is an Output?
The output is the number that comes out after the rule runs. In the pair "3 in, 7 out", the output is 7. Comparing inputs with outputs is how you work out the hidden operation. If the output matches your prediction, your rule is probably right.
Rules You Can Practice
Easy rules
One-step addition and subtraction, like "add 2" or "subtract 3". These fit grades 2 and 3. Start here if your child is new to patterns.
Medium rules
Multiplication and division, like "multiply by 2" or "divide by 2". These fit grades 3 through 5 and build strong number fluency.
Challenge rules
Two-step rules, like "multiply by 2, then add 1". They need careful testing, make a great brain workout, and suit students who finish the medium levels quickly.
Choose Your Input Output Game
Games for Kids
Pick a game for your child and get simple tips for practicing math at home.
Games for KidsLearn the Rule in 3 Steps
Look at the clue
Each pair shows a number that went in and the number that came out. If 3 goes in and 7 comes out, the hidden rule could be "add 4". Notice the change before you guess.
Test a number
Send in your own number. A second pair can rule out a tempting wrong answer. Test 5 next: if 9 comes out, "add 4" still works. If it does not, your first guess was just a lucky match.
Choose the rule
Pick the operation that works for every pair, not just the first one. Check at least two pairs, then name the rule with confidence, like "the rule is add 4".
Use Input Output Games in Your Classroom
Input output games are a fast, low-prep way to warm up algebraic thinking. Students watch numbers change under a rule, make a guess, test it, and fix it when they are wrong. That loop is exactly the thinking they will need later for equations and functions, and it turns a mistake into useful information instead of a bad grade.
The games give instant feedback, so students can practice on their own while you help a small group. Everything here is free and needs no account. Pair the games with the free printable worksheet on the tables page, and share the tips for practicing at home with families.
Try a whole-class round first, then let students pick their level and play at their own pace. Watch how they choose test numbers: the questions they ask tell you what they understand and what they still need to learn.
Morning warm-up
Project the function machine on a smartboard and let the class take turns testing numbers while everyone predicts the output.
Math center
Set up tablets at a center. Automatic feedback means every wrong answer becomes a clue, not a red mark.
Homework option
Suggest a five-minute game as a light task. The printable worksheet on the tables page works without a screen too.
Early finishers
Challenge fast finishers with two-step rules like "multiply by 2, then add 1" to stretch their thinking.
Function Machine FAQ
What is an input output game?
An input output game gives you a number that goes in and a number that comes out. Your job is to find the math rule that connects them, like add 4 or multiply by 3.
What grade level is this game for?
The easiest levels fit grades 2 and 3. Multiplication, division, and two-step rules fit grades 3 through 5. Players can pick the level that matches their skill.
Do students need an account to play?
No. Every game on this site is free and works without signing up, so students can start playing right away.
Can I use these games on a tablet or smartboard?
Yes. The games work on phones, tablets, laptops, and smartboards. The buttons are big enough for small hands.
How do input output tables work?
An input output table shows rows of inputs and outputs made by the same rule. Complete the missing numbers by finding the rule that fits every row.
What math rules can I practice?
You can practice one-step addition, subtraction, multiplication, and division rules, plus two-step rules like "multiply by 2, then add 1". Easy levels fit grades 2 and 3, and harder levels stretch up to grade 5.
Why do input output games help with algebra?
Finding a rule by testing numbers is the same skill algebra asks for later: spot the pattern, test a guess, and prove it works. Students build confidence with numbers long before they meet letters and equations.
Do you have free printable worksheets?
Yes. The input output tables page has a free PDF worksheet with six problems and an answer key. It is perfect for centers, homework, or a quick warm-up without a screen.
Can these games be used in a classroom?
Absolutely. The games work on smartboards, tablets, and laptops, and they never need an account. Teachers can pair them with the printable worksheet or point families to our parent tips page.
Do I need to download or install anything?
No. Every game runs right in your browser on a phone, tablet, or computer. There is nothing to install and no account to create, so a child can start playing in seconds.