Subtracting to 10 · Kode bersama Martin

Minus takes away from a pile

You have seven sweets. You eat two. How many are left? You take two from the pile and count the rest: five. You just subtracted.

Subtracting is written with the minus sign: −. The writing 7 − 2 = 5 you read: seven minus two equals five. It means: from seven things I take two away and five are left.

The result of subtracting is called the difference.

You meet minus as often as plus. A snack got eaten. Marbles got lost in a game. Crowns got spent. Each time something was there, something went away and you want to know how many are left. You will count it on bricks, on fingers and by jumping backwards on the number line.

Watch out, subtracting is different from adding in one important way: you must not swap the numbers. 7 − 2 is not the same as 2 − 7. You always start with what you have, and take away from that. The big number is at the front.

Sofie has 8 stickers. Ema likes three of them, so Sofie gives them to her. “How many do you have left?” asks Ema. Sofie counts the stickers one by one: five. Then she tries another way, like on a number line: “Eight… seven, six, five! Three jumps back.” Ema stares: “You count backwards?” “Sure. Minus is jumping left.” From then on they both play crocodile, jumping backwards along a ruler and hissing: seven, six, five! Whoever slips up passes the ruler to the other. Sofie is winning so far — backwards she already counts almost as fast as forwards.

💡

Minus is jumping left on the number line. How many you take away, that many jumps back you make.

How to subtract step by step

Example: 8 − 3. Again you have three paths.

Path 1: taking from a pile. Put down 8 bricks. Slide three away. Count what is left: 1, 2, 3, 4, 5. The difference is 5.

Path 2: counting backwards. Keep eight in your head. Put up three fingers. Count backwards, one number for each finger: seven, six, five. 5 is left.

Path 3: jumping left on the line. Stand on 8. Three jumps left: 7, 6, 5. You are on five.

And a fourth path for clever kids: subtracting is adding backwards. You ask: three and how many is eight? You know that 3 + 5 = 8. So 8 − 3 = 5. If you add well, you get subtracting for free.

The writing: big number, minus, what you take away, equals, difference. 8 − 3 = 5.

Always check the result by adding: 5 + 3 = 8? Yes. So the difference is right.

9 − 4 = ?

I count backwards.

Nine in my head. Four fingers up.

Eight, seven, six, five. The fingers are used up.

9 − 4 = 5.

Check by adding: 5 + 4 = 9? Five… six, seven, eight, nine. Yes! The difference is right.

10 − 7 = ?

Seven jumps backwards is a lot. I use a smarter path: adding backwards.

I ask: seven and how many is ten? I know the pairs to ten: 7 + 3 = 10.

So 10 − 7 = 3.

See what the pairs to ten are for? If you know them, you subtract from ten in a flash.

6 − 6 = ?

I have six sweets and I eat all six. How many are left?

I take them all away. The pile is empty. Nothing is left — and nothing is the number zero.

6 − 6 = 0.

When you subtract a whole number from itself, you always get zero. There will be a whole lesson just about zero.

⚠️

Never swap the numbers with minus. 3 − 8 is not the same as 8 − 3. At the front is always what you have. Taking away more than you have is something we cannot do yet.

Practice: now you do it 🎲

Now try it for real. You will see all the questions at once, like on paper. Mulai with ten. If it goes well, add more.

Subtract to 10. Count backwards or use the pairs.

Practise the questions

On paper

Paper, a pencil and ten bricks for taking away.

Calculate and write: 8 − 5, 9 − 2, 10 − 6, 7 − 7.
Check each result by adding. For example: 8 − 5 = 3, so check 3 + 5 = 8.
Put down 10 bricks. Take away two at a time and write: 10 − 2 = 8, 8 − 2 = 6… down to zero.
Make up a subtracting question about a snack and calculate it.

Now you 💪

I know that minus means take away and the result is the difference.
I can count backwards and jump left on the line.
I can check a subtracting result by adding.

✅

Done when: You calculate five subtracting questions to 10 and check each one by adding.

What to take from this lesson

Minus = take away. The result is the difference.
The big number is at the front. Do not swap numbers with minus.
Minus is jumping left on the line.
Subtracting is adding backwards: 8 − 3? Ask how many three needs to reach eight.
Check: difference plus the number taken away must give the original.