How many more, how many less · Code with Martin

Comparing with a number: not only who has more, but by how many. The difference of two piles.

Not only who won, but by how many

You have 9 marbles, a friend has 6. That you have more, you can see. But how many more?

Subtracting answers that. 9 − 6 = 3. You have 3 more marbles. And your friend has 3 fewer. It is one and the same number — the difference.

Questions “how many more” and “how many less” you meet all the time. How many years older is your brother? How many Kč more does the ice cream cost? How many goals did you win by?

Difference is a useful number. It tells you if a race was close, or clear. If a toy is one Kč more, or fifty. A small difference means almost the same. A big difference means a big lead. Without the difference you only see the winner — with the difference you see the whole story.

You always find the answer the same way: from the bigger number you subtract the smaller one. Or you ask: how many must I add to the smaller one so it catches the bigger one? Both paths lead to the same difference.

Ema jumped from standing 85 centimetres, Filip 79. “I won!” Ema reports. “But by how many?” asks Filip. “Who cares, the main thing is I’m first.” Filip disagrees: “It does care. How many tells you if it was a close fight.” He counts: from 79 to 85 is missing… 79 and 1 is 80, and 5 more is 85. “Only six centimetres! Next time I’ll beat you.” Ema laughs: “All right. Difference six, close fight.” They jump three more times. Filip gets a bit better each time and the difference shrinks: six, four, two centimetres. The numbers cheer with them.

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“How many more” = subtract the smaller number from the bigger one. Or fill up: how many does the smaller one need to reach the bigger one?

You find the difference in two ways

Question: Adam has 12 stickers, Tereza 8. How many more does Adam have?

Path 1: subtract. Bigger minus smaller: 12 − 8 = 4. Adam has 4 more.

Path 2: fill up. From 8 to 12: 8 and 2 is 10, 10 and 2 is 12. Together 4. Same result.

You can draw the difference too. Two rows of circles under each other: a row of twelve and a row of eight. Pair them. Four circles are left with no pair — that is the difference.

Watch two things:

First: “how many more Adam has” and “how many fewer Tereza has” is the same number. There is only one difference. You look at it from two sides.

Second: always subtract the smaller from the bigger. A “how many” question does not have a negative answer.

And watch a different question: “how many times more” is something else than “how many more”. How many times — that is multiplying, that waits for you at Times-table kid. Right now we can do “how many more” — and that is subtracting.

Ice cream for 25 Kč, an ice lolly for 18 Kč. How much more does the ice cream cost?

The bigger number is 25, the smaller 18.

I subtract: 25 − 18. Through ten: 25 − 5 = 20, then 20 − 3 = 7.

The ice cream costs 7 Kč more.

Check by filling up: from 18 to 25? 18 and 2 is 20, 20 and 5 is 25. Together 7. It matches.

And the other way is true too: the ice lolly is 7 Kč cheaper. One difference, two sentences.

Jonáš is 8 years old, his sister 14. How many years older is the sister?

Bigger number 14, smaller 8.

I fill up: from 8 to 14. Eight and 2 is 10. Ten and 4 is 14. Together 2 + 4 = 6.

The sister is 6 years older.

Check by subtracting: 14 − 8 = 6. It matches.

And in ten years? The sister will be 24, Jonáš 18. The difference is 6 again. The age difference does not change — both grow the same.

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Do not mix “how many more” with ordinary “how many do they have together”. Together = adding. How many more = subtracting. Read the question twice before you start counting.

Practice: now you do it 🎲

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

How much bigger is one number? Numbers to 20.

Practise the questions

On paper

Paper, a pencil and crayons for drawing rows.

Draw two rows of circles: 11 and 7. Pair them and write the difference.
Calculate: how much bigger is 45 than 30? How much smaller is 16 than 24?
Find the age difference between you and someone in your family. Write the whole question.
Make up a “how many more” question about the prices of two treats and answer it.

Now you 💪

I know that “how many more” means subtract the smaller from the bigger.
I can find the difference by filling up from the smaller number too.
I do not mix “how many more” and “how many together”.

✅

Done when: You solve three “how many more” problems and for one you show both paths: subtracting and filling up.

What to take from this lesson

“How many more” is solved by subtracting: bigger minus smaller.
Second path: fill up from the smaller to the bigger.
How many more one has = how many less the other has.
You can draw the difference: pair two rows of circles.
“Together” is plus, “how many more” is minus. Read the question carefully.