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3rd grade multiplication · Unit 7

Use AI to help with missing number problems

You use the AI. Your child does the thinking. This page explains how the class teaches missing number problems and what to say tonight, and it has a free practice sheet with the answer key on its own page.

If you use AI: snap one problem, get help and more practice

Already seeing your child photograph homework so AI can solve it? This box is the grown-up version: the AI gives you hints and new practice, and your child still works the problem on paper.

For a problem that isn’t like the ones on our sheet, use your own AI account to get it explained and get 5 more like it. The photo goes to your AI account and never reaches AiWhizzkids.

Where AI can go wrong on this skill

AI may turn every practice problem into the same form, like 42 ÷ 7 = ?, when the worksheet hides a different number. Check that the new problems keep the missing number in the same place as tonight’s homework.

  1. Photograph one printed problem only. Crop out your child’s name, school, teacher and handwriting.
  2. Open your own AI account (ChatGPT, Gemini or similar). Most require users to be 13 or older, so you hold the phone.
  3. Upload the photo and paste this prompt:
    This is a math problem from my child's 3rd-grade homework. Please help me, the parent.
    1. Type the problem back exactly as you see it, including any words. If a picture, table or diagram is part of it, describe it in words. If anything is unclear or cut off, say so instead of guessing.
    2. Tell me what kind of problem this is (for example a two-step word problem, the distributive property, regrouping or an area model) and which strategy the worksheet seems to want.
    3. Explain that strategy to me in plain words, the way a 3rd-grade teacher would, in 5 sentences or fewer. Don't use a shortcut my child hasn't learned.
    4. Give me 3 questions I can ask my child to get started. Hints only, no answers.
    5. Write 5 new practice problems of the same type, with the same strategy and the same size of numbers. Number them. No answers next to them.
    6. Put an answer key at the very end, with one line of working for each.
    Don't solve the original problem. My child will do that.
    Show each one as an equation with one missing number, and link it to the multiplication fact that finds it.
  4. Check before you print:
    • Does the problem it typed back match the photo exactly?
    • Did it name the same strategy your child’s worksheet uses?
    • Work one new problem yourself and compare it with the key.
    • If the problem has a picture (an array, a number line, a clock), check the AI’s description of it. If the description is wrong, type the problem out instead of using the photo.
    • If anything looks off, ask again in a new chat. If two answers differ, trust neither.
    • Put the answer back in the equation. Is it true?

Your child works on paper. Follow your school’s AI rules.

How your child’s class teaches it

A missing number problem gives your child two of the three numbers in a fact and asks for the third. The missing one can be anywhere: ? × 7 = 42, 8 × ? = 56 or 48 ÷ ? = 6. Worksheets often show it as a box or a question mark.

? × 7 = 42: 6 rows of 7 make 42, so the missing number is 6.

Your child solves it with a fact they know. For ? × 7 = 42, they ask, “How many 7s make 42?” Skip-counting by 7 gets there: 7, 14, 21, 28, 35, 42. That’s six 7s, so the missing number is 6.

Division works the same way, and it’s how 3rd grade teaches division facts. 54 ÷ 9 = ? becomes “9 times what makes 54?” Since 9 × 6 = 54, the answer is 6. When the first number is missing, as in ? ÷ 5 = 8, the missing number is the total: 5 × 8 = 40.

In the Common Core standards, missing numbers are 3.OA.4, and division as a missing factor is 3.OA.6. Texas, Florida, Virginia and some other states use their own standards, so follow the method on your child’s worksheet.

What to say tonight

“Which number is missing? Which two do you know?”

“What multiplication fact uses these numbers?”

“Put your answer in the box. Is the equation true now?”

The mistake to watch for

The usual slip is doing the operation that’s written, with the numbers that are there. For ? × 7 = 42, your child multiplies 7 × 42 and writes 294. Ask, “What number times 7 makes 42?”

In division, watch problems like ? ÷ 5 = 8. The missing number is the total, so it’s bigger than both numbers you can see. Have your child check the answer: does 40 ÷ 5 make 8?

Free practice sheet

The sheet has 10 problems on one page: 4 multiplication facts with a missing number, 3 division facts with a missing number and 3 divisions to solve by thinking of a multiplication fact. The answer key is on page 2, so you can print page 1 on its own.

Page 1 of the missing numbers practice sheet: four multiplication facts and three division facts with a box for the missing number, and three divisions to solve.
Download the sheet (PDF)

Free to print for your family or one classroom. No email needed. Every answer on the key is computed by code.

Doing this every night? The Grade 3 Multiplication Catch-Up Plan is three weeks of 10-minute printable sessions, with answer keys checked in code. It’s $14.99 and ready to print. See the plan on Payhip

Rather skip the AI account? We’re thinking about building the photo step into this page.

Snap your worksheet (beta)

It isn’t built yet. The idea: you take a photo of one printed problem, and this page names the problem type and makes matching practice with an answer key, with no AI account of your own. If you’d use it, join the waitlist. If enough parents want it, we’ll build it and email you first.

Your email is the only thing we keep. Nothing is uploaded, and nothing about your child is collected. You’ll also get our emails for parents, and you can unsubscribe whenever you like.

AiWhizzkids is not affiliated with or endorsed by OpenAI, Google, Microsoft or Anthropic. Most AI chatbots require users to be 13 or older (Claude requires 18), and these guides are for parents using their own accounts. AI can be wrong, so check its answers. Follow your school’s AI policy.

Checked by AiWhizzkids on October 27, 2026. Drafted with AI help. Every answer key is computed by code.

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