Input Output Tables
Updated October 2026 · 11 free printables
Function tables with a rule like +4 or x3: kids use the rule to fill in the missing In and Out numbers, or look at the table and work out the rule themselves.
Also here: addend tables (addend + addend = sum) and subtraction tables with minuend, subtrahend and difference, a classic textbook exercise that builds fact fluency and math vocabulary.
All 11 Input Output Tables, One by One
Here is a closer look at every page in this collection: what it practices, which grade it fits and a tip for each one.
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1. Addition Tables to 10
A free printable addition tables to 10 worksheet with an answer key. In each column, addend + addend = sum. Fill in the empty boxes. It matches first grade goals, roughly ages 6 to 7. Read the rule out loud before filling in a table.
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2. Addition Tables to 20
A free printable addition tables to 20 worksheet with an answer key. In each column, addend + addend = sum. Find the missing numbers. First graders can do it on their own once they know the strategy at the top of the page. Check each column with the opposite operation.
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3. Subtraction Tables to 20
A free printable subtraction tables to 20 worksheet with an answer key. In each column, minuend - subtrahend = difference. Fill in the empty boxes. First graders can do it on their own once they know the strategy at the top of the page. Check each column with the opposite operation.
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4. Input Output Tables: Addition
A free printable input output tables: addition worksheet with an answer key. Use the rule to find each missing In or Out number. First graders can do it on their own once they know the strategy at the top of the page. Check each column with the opposite operation.
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5. Input Output Tables: Addition (Set 2)
A free printable input output tables: addition (set 2) worksheet with an answer key. Use the rule to find each missing In or Out number. First graders can do it on their own once they know the strategy at the top of the page. Check each column with the opposite operation.
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6. Addition and Subtraction Tables to 100
A free printable addition and subtraction tables to 100 worksheet with an answer key. Fill in the empty boxes. Check each column with the opposite operation. Second graders usually finish it in 10 to 15 minutes. Check each column with the opposite operation.
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7. Addition and Subtraction Tables to 100 (Set 2)
A free printable addition and subtraction tables to 100 (set 2) worksheet with an answer key. Fill in the empty boxes. Check each column with the opposite operation. Second graders usually finish it in 10 to 15 minutes. Check each column with the opposite operation.
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8. Input Output Tables: Add and Subtract
A free printable input output tables: add and subtract worksheet with an answer key. Use the rule to fill in the table. Some rules add, some subtract. Second graders usually finish it in 10 to 15 minutes. Check each column with the opposite operation.
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9. Find the Rule Tables
A free printable find the rule tables worksheet with an answer key. Look at the In and Out numbers, write the rule, then finish the table. It fits second grade, around ages 7 to 8. Read the rule out loud before filling in a table.
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10. Find the Rule Tables (Set 2)
A free printable find the rule tables (set 2) worksheet with an answer key. Look at the In and Out numbers, write the rule, then finish the table. It fits second grade, around ages 7 to 8. Read the rule out loud before filling in a table.
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11. Input Output Tables: Multiplication
A free printable input output tables: multiplication worksheet with an answer key. Multiply by the rule to fill in the missing numbers. Third graders can use it for practice, review or a quick check before a test. Check each column with the opposite operation.
Tips for input output tables
- Read the rule out loud before starting: plus 4, times 3.
- To find a missing In number, do the opposite of the rule.
- To find the rule, compare one In with its Out and test the idea on another row.
Fun math facts
- Input output tables are an early introduction to functions, a big idea in algebra.
- Some textbooks call them function machines or 'What's my rule?' tables.
- Addend tables are a classic exercise in European textbooks, with the rows term, term and sum.
Fun ways to use your printables
- Build a cardboard 'function machine': put a number card in, and a partner applies the rule.
- Make up a secret rule and let your child guess it from three examples.
- Use real prices: if a sticker costs 3 cents, fill in a table for 1 to 5 stickers.
How to print
Click Download PDF and print at 100% on US Letter or A4 paper. Page 1 is the worksheet and page 2 is the answer key, so choose “page 1” in the print dialog if you only want the practice page. Every worksheet is free for home, homeschool and classroom use, so print as many copies as you need.
Frequently asked questions
What is an input output table?
A two-column table with a rule. Each In number goes through the rule to make the Out number: with the rule +5, an In of 3 gives an Out of 8.
How do you find the In number?
Do the opposite of the rule. If the rule is +5 and the Out is 12, the In is 12 - 5 = 7.
What do minuend and subtrahend mean?
In 9 - 4 = 5, 9 is the minuend, 4 the subtrahend and 5 the difference.