Super Sleuth Division: Dividing “Tens Numbers” in Your Head!

Hello Division Detectives! Get ready to use your amazing maths brains for a super-smart division trick! Today, we’re learning how to mentally divide a “tens number” (a multiple of 10, like 20, 30, 80, 90) by a one-digit number. If you know your basic division or multiplication facts, this will be a piece of cake!

The Secret Trick: Think “Tens” and Use Your Basic Facts!

When you see a problem like 80 ÷ 4, the zero on the end of 80 is a big clue! It tells you we’re dealing with tens.

Here’s the main idea:

1. Ignore the zero for a moment and look at the basic division fact.
2. Solve that basic fact.
3. Then, put the zero back on (or think about it as “tens”).

Let’s Solve: 80 ÷ 4

Here’s how to use the trick:

• The Problem: We want to solve 80 ÷ 4.
• Step 1: Cover the zero (mentally!). If we cover the zero in 80, we see the number 8.
• Step 2: Do the basic division fact. Now, what is 8 ÷ 4?
  • We know 8 ÷ 4 = 2 (because 2 × 4 = 8).
• Step 3: Put the zero back (or think in tens!). Since our original number was 80 (which is 8 tens), our answer will be 2 tens.
  • 2 tens is 20.
• The Answer: That means 80 ÷ 4 = 20!

You can also think of it as: “80 is 8 tens. If I share 8 tens into 4 equal groups, each group will have 2 tens. And 2 tens is 20!”

Another Example: 60 ÷ 3

• Problem: 60 ÷ 3
• Step 1: Cover the zero. We see 6.
• Step 2: Basic division fact. 6 ÷ 3 = 2.
• Step 3: Put the zero back (or think in tens). 60 is 6 tens. So, 6 tens ÷ 3 = 2 tens. 2 tens is 20.
• Answer: So, 60 ÷ 3 = 20.

Using Reverse Multiplication (Inverse Operations!): For 80 ÷ 4 = ?, you can ask yourself: “What number times 4 equals 80?”

• You know ? × 4 = 8. The answer is 2.
• So, for ? × 4 = 80, the answer must be 20!

Practice Your Smart Division! (18 Challenges)

Ready to try this cool mental trick for dividing tens numbers? For each problem below, use the strategy of looking at the basic fact first, then remembering it’s tens you’re working with!

(Your web app with the 18 questions will go here. Questions should be like “90 ÷ 3 =”, “120 ÷ 6 =”, “70 ÷ 7 =”, encouraging the mental strategy.)

Why is This Mental Division Trick So Clever?

• Uses Facts You Know: It connects directly to your basic division and multiplication facts.
• Super Quick for Mental Maths: Once you get it, you can solve these problems very fast in your head.
• Builds Place Value Understanding: You see how dividing 8 tens is different from dividing 8 ones.
• Great for Checking Multiplication: It helps reinforce the link between multiplication and division.

Tips for Grown-Ups: Helping with Dividing Multiples of 10

This mental division strategy relies on children’s understanding of basic division/multiplication facts and place value (specifically, that 80 is 8 tens).

• Ensure Basic Facts are Strong: Children need to be comfortable with their division facts (e.g., 8÷4, 6÷3) for this to be effective.
• Use “Tens” Language: Encourage them to articulate the problem as “8 tens divided by 4 equals 2 tens.” Then help them convert “2 tens” back to “20.”
• Link to Multiplying by 10: Show them how this is the inverse of the strategy for multiplying a single digit by a multiple of 10 (e.g., if 6×20 = (6×2)×10 = 120, then 120÷6 = (12÷6)×10 = 2×10 = 20. Or for 80÷4: think ?x4=80. We know 2×4=8. So 20×4=80. Answer is 20).
• Concrete Representation (If Needed): Use base-ten blocks. Show 8 ten-rods. “If we divide these 8 ten-rods into 4 equal groups, how many ten-rods are in each group?” (2 ten-rods, which is 20).
• Verbalise the “Cover the Zero” Trick: While it’s a shortcut, ensure they understand why it works because of the place value (dividing tens gives an answer in tens).