Add & subtract
Best for new pattern finders and grades 2–3.
Free math game · No sign-up
Input Output Games Online
Crack the Function Machine! Send in test numbers, compare the outputs, and uncover the secret math rule.
- Four learning levels
- Works on phones and tablets
- Instant, kid-friendly feedback
Ready, number detective?
Play the Function Machine Game
Start with the example, run your own tests, then choose the rule that explains every output.
Input
3
Secret rule
?
Output
9
1
Test the machine
Try up to 6 numbers to spot the pattern.
Your tests will appear here
2
Guess the secret rule
Which rule works for every number?
Use the example or run a test before you guess.
Learn the pattern
How to Play Input Output Games
A function machine follows one rule every time. Your job is to discover that rule from the clues.
- 1
Study the clue
Look at the first input and output pair. Ask what math could connect them.
- 2
Test a number
Enter your own input. One extra pair can rule out a tempting wrong answer.
- 3
Choose the rule
Pick the operation that works for every pair—not just the first example.
Quick practice
Input Output Table Game
Input output tables show the same function rule across several rows. Complete this table using the rule + 4.
Fill all three boxes, then check your table.
Grow one step at a time
Choose the Right Function Machine Level
Build confidence with one operation, then move into multi-step thinking when you are ready.
Multiply & divide
Practice fact families and inverse operations.
Two-step rules
Follow rules such as “multiply by 2, then add 3.”
Mixed & timed
Use every strategy while the clock counts down.
Questions from families & teachers
Function Machine FAQ
Short answers for helping children understand input output rules.
What is an input output function machine?
An input output function machine applies the same math rule to every number that goes in. For example, a machine with the rule “multiply by 3” turns an input of 4 into an output of 12.
How do input output tables work?
Each row pairs an input with the output created by one consistent rule. Compare several rows, identify what changes, and use the rule to complete missing values.
What grade level is this input output game for?
Easy addition and subtraction rounds work well for grades 2 and 3. Multiplication, division, and two-step rules support students in grades 3 through 6.
Why should children test more than one input?
One pair may fit several possible rules. Testing a second or third input provides stronger evidence and helps children explain why their answer must be correct.
Is this math game free?
Yes. The Function Machine game is free to play in a web browser, with no account or download required.