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Turn your own number worksheets into math flashcards up to 20

Printable sheets cover facts someone else picked. Upload the worksheet, notes or photo your class is using and get flashcards that match it, then study them in your browser.

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Practice addition and subtraction within 20 with your own material

Kids learning to add and subtract within 20 often need many short, repeated drills, and math flashcards up to 20 are a long-standing way to get those facts to stick. A ready-made printable set can help, but it only covers the problems its author chose.

Number recognition and counting on from any number within 20
Doubles and near doubles, such as 6 + 6 and 6 + 7
Make-ten strategies for addition and subtraction facts
Mixed subtraction facts that count back from numbers up to 20

Example addition and subtraction flashcards within 20

What is 8 + 7?15. Make ten first: 8 + 2 = 10, then add the remaining 5 to get 15.

What is 14 - 6?8. Count back 6 from 14, or think 6 + 8 = 14.

What is 9 + 9?18. This is a double, and doubles are worth memorizing early.

What number is 10 more than 6?16. Adding 10 changes only the tens place, so 6 + 10 = 16.

What is 20 - 12?8. Subtract 10 to get 10, then subtract 2 more to get 8.

Generate the full set

Upload your own material

Add PDFs, DOCX or PPTX files, plain text notes, or photos of a page read with text recognition.

Spaced repetition on Plus

Plus adds spaced repetition so the cards a learner misses come back sooner and the ones they know come back later.

Quizzes and mind maps too

From the same material you can also get multiple choice, true/false and short answer quizzes with explanations, plus mind maps.

How it works

Add your material

Upload a worksheet photo, a PDF, or typed notes from the lesson.

Generate the cards

DeckOwl builds flashcards from the numbers and facts on your pages.

Study in the browser

Practice on the free plan, or export to PDF or Anki on Plus when you want printed or app-based cards.

DeckOwl works from the pages your child or class actually uses, so the cards match the exact problem types on the worksheet. The free plan includes 3 generations per month with browser study. Plus, at $39 per year or $7.99 per month, adds unlimited generations and PDF, DOCX, Anki and CSV export, and students with a school email get 40% off.

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Frequently asked questions

How many math flashcards up to 20 should a child practice at once?

Short sessions of about 10 to 15 cards are a common starting point for young learners. Mix a few new cards in with ones the child already knows so practice feels manageable.

Which addition and subtraction facts within 20 should kids learn first?

Start with counting on from any number and recognizing numbers, then move to doubles like 4 + 4 and make-ten pairs like 7 + 3. Subtraction facts that count back from numbers up to 20 usually come after those.

Can I print the flashcards I make?

Printing needs a PDF export, which is included in Plus at $39 per year or $7.99 per month. Cards on the free plan can only be studied in the browser.

Does it work with a photo of a worksheet?

Yes, photos of pages are read with text recognition. You can also upload PDF, DOCX, PPTX or plain text notes.

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Keep exploring the topic

Review the main ideas visually or practice recalling them.