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3rd grade multiplication · Unit 8

Use AI to help with multiplying by tens

You use the AI. Your child does the thinking. This page explains how the class teaches multiplying by tens 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 teach “just add a zero,” the shortcut many classes avoid. Check that it explains the answer in tens, like 7 × 40 = 28 tens = 280.

  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 groups of tens, like 7 × 40 = 7 × 4 tens = 28 tens = 280, and keep the multiples of 10 between 10 and 90.

    If it’s a story problem, add this line to the end of the prompt too:

    Keep the same kind of story and the same operations, but change the names, things and numbers. Make one problem include an extra number that isn't needed.
  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.
    • Does each answer match its fact, counted in tens?
    • For a story problem, read each new problem. Does it make sense, and does it need the same operation?

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

How your child’s class teaches it

In 3rd grade, children multiply a one-digit number by a multiple of 10, like 7 × 40. Classes teach it with tens: 40 is 4 tens, so 7 × 40 is 7 groups of 4 tens. That’s 28 tens, and 28 tens is 280.

3 × 40: 3 groups of 4 tens is 12 tens, or 120.

So your child starts from a fact they already know, 7 × 4 = 28, and counts in tens instead of ones. Worksheets often show the tens as sticks or as base-ten blocks.

You may have learned this as “just add a zero.” Many teachers avoid that shortcut, because it stops working with decimals in later grades, so the class talks about tens instead. If your child’s worksheet says “28 tens,” that’s why.

Florida’s 3rd graders also multiply by multiples of 100, like 4 × 300. It works the same way: 4 groups of 3 hundreds is 12 hundreds, or 1,200.

In the Common Core standards, this is 3.NBT.3. Texas, Florida, Virginia and some other states use their own standards, so follow the method on your child’s worksheet.

What to say tonight

“How many tens are in 40?”

“What fact do you already know that helps?”

“So how many tens is that altogether? What number is that?”

The mistake to watch for

The usual slip is forgetting that the answer is tens. Your child works out 7 × 4 = 28 and stops there. Ask, “Is that 28 ones or 28 tens?”

Watch the facts that already end in zero, too. 6 × 50 is 30 tens, which is 300, with two zeros. A child who learned “add one zero” may think 300 must be wrong and change it to 30.

Free practice sheet

The sheet has 10 problems on one page: 4 pictures of tens to count, 3 facts to use and 3 story problems. The answer key is on page 2, so you can print page 1 on its own.

Page 1 of the multiplying by tens practice sheet: circles of ten-sticks to count, three facts to finish and three story problems.
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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