Super Smart Multiplication: Multiplying by Tens Numbers in Your Head!

Hello Multiplication Masters! Get ready to learn a super clever trick that makes multiplying a single-digit number by a “tens number” (like 20, 30, 40, 50, etc.) really easy to do in your head. It’s all about breaking the problem into smaller, friendlier steps!

The Secret Trick: Break It Down, Then Multiply by 10!

When you see a problem like 6 × 20, it might look a bit big at first. But here’s the secret: A number like 20 is just 2 × 10. A number like 30 is just 3 × 10. A number like 70 is just 7 × 10.

So, we can use this to help us!

Let’s Solve: 6 × 20 (Thinking 6 × 2 × 10)

Here’s how to use the trick:

• The Problem: We want to solve 6 × 20.
• Step 1: Break down the multiple of 10. Think of 20 as 2 × 10.
• Step 2: Multiply the single digits first. Now take your first number (6) and multiply it by the first digit of your broken-down tens number (which is 2).
  • So, do 6 × 2.
  • 6 × 2 = 12.
• Step 3: Multiply your answer by 10. Now take your answer from Step 2 (which is 12) and multiply it by 10. Remember, multiplying by 10 is easy – you just add a zero to the end (or move the digits one place to the left if you’re thinking about place value)!
  • So, 12 × 10 = 120.
• The Answer: That means 6 × 20 = 120!

You did it! You solved it by doing 6 × 2 first, and then multiplying that answer by 10.

Another Example: 4 × 50

• Problem: 4 × 50
• Step 1: Break down 50. Think of 50 as 5 × 10.
• Step 2: Multiply single digits. 4 × 5 = 20.
• Step 3: Multiply by 10. 20 × 10 = 200.
• Answer: So, 4 × 50 = 200.

Practice Your Smart Multiplication! (18 Challenges)

Ready to try this cool mental trick? For each problem below, multiply the single-digit number by a multiple of 10. Remember to break down the tens number, multiply the first parts, and then multiply by 10!

(Your web app with the 18 questions will go here. Questions should be like “7 × 30 =”, “5 × 80 =”, etc., encouraging the mental strategy.)

Why is This Mental Multiplication Trick So Useful?

• Makes Big Problems Simpler: It turns a tricky multiplication into two easier steps.
• Uses Facts You Already Know: You use your basic multiplication facts (like 6×2) and your easy ×10 skill.
• Super Fast for Mental Maths: Once you get the hang of it, you can do these very quickly in your head.
• Boosts Your Confidence: Solving these makes you feel like a mental maths whizz!

Tips for Grown-Ups: Helping with This Mental Strategy

This mental multiplication strategy uses the associative property of multiplication (a × (b × c) = (a × b) × c) and leverages children’s knowledge of basic facts and multiplying by 10.

• Ensure Multiplying by 10 is Secure: Before teaching this strategy, make sure the child is very comfortable with multiplying any number by 10 (knowing to add a zero or shift digits).
• Explicitly Show the Breakdown: Write it out at first: 6 × 20 = 6 × 2 × 10. Circle the “6 × 2” part to do first.
• Verbalise the Steps: Encourage children to say the steps aloud: “First I’ll do 6 times 2, that’s 12. Then I’ll do 12 times 10, that’s 120.”
• Connect to Place Value: Explain that when they multiply by 20, they are finding “6 groups of 2 tens.” 6 groups of 2 tens is 12 tens, and 12 tens is 120.
• Practice with Various Multiples of 10: Use examples with 20, 30, 40, 50, 60, 70, 80, 90.