Turn any worksheet into missing number flashcards
Upload a PDF, slides, notes or a photo of a page. DeckOwl writes flashcards that keep the blank in place, so you practice the exact problems your teacher assigned.
Why missing number practice works better with your own problems
Children practicing addition, subtraction and skip counting need repeated exposure to the same facts in different positions, and missing number flashcards build that flexibility better than reading a single answer key. A card asking for the blank in 7 + __ = 10 trains the same skill as one asking for the blank in __ + 3 = 10.
- Blanks in any position: first, middle or last term of a sequence or equation
- Number patterns such as counting by twos, fives or tens
- Missing addends, subtrahends, minuends and factors in one deck
- Quizzes with explanations that show the rule behind each answer
Blanks from your own sheets
Upload a worksheet or a photo of the board and the cards keep the blank where the number belongs.
Spaced repetition
Cards you miss come back sooner, so number facts stick across several days of practice.
Export when you need it
PDF, DOCX, Anki and CSV exports are part of the Plus plan.
How it works
Upload
Add a PDF, DOCX, slides, plain notes or a photo of a page.
Generate
DeckOwl writes question cards with the missing value as the answer.
Study
Review in your browser on a daily schedule, or export the deck to Anki.
Printed sheets cover the topics a publisher chose, in the order they chose. Upload your own worksheet, a class handout or a photo of the board and DeckOwl builds cards from those exact problems, so practice matches what was assigned. Cards you get wrong return sooner through spaced repetition, which keeps last month's facts from slipping.
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Frequently asked questions
How do I find a missing number in a sequence?
Look at the difference between neighboring terms. If the numbers rise by the same amount each step, add that amount to the term before the blank; in 20, 25, __, 35 the step is 5, so the answer is 30.
How many missing number problems should a child practice per day?
Ten to fifteen problems in a short session is a reasonable start, with a quick review of missed items the next day. Spreading practice over several days works better than one long session.
Can I print missing number flashcards instead?
PDF export is part of the Plus plan at $99.90/year or $9.99/month. The free plan lets you study generated cards in the browser, with three generations per month.
Is there a discount for students?
Students with a school email get 40% off, and no credit card is needed to start on the free plan.
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