seegongsik
Grade 1 (age 6-7)

grade 1 Subtraction Basics

Subtraction is taking some away from a whole and finding how many are left. If you have 7 cookies and eat 3, then 4 remain; we write it with the minus sign: 7 − 3 = 4. If you know 3 + 4 = 7, you also know 7 − 4 = 3, so addition and subtraction are partners. Slide the cookies and how many are eaten, then move left along the number line to count what stays.

What does taking away mean?

✂️ Taking away is subtracting
①There were 5 cookies, and you ate 2
②3 cookies are left
③Taking some away and finding how many are left is called subtraction
④We write taking away with the minus sign −

Eat some cookies

7
3
💡 Left and eaten
①The cookies that are left are on the left, and the eaten ones are on the right
②Each eaten cookie has a red X on it
③7 − 3 = 4 is read "seven minus three equals four"
④Set the eaten cookies to 0 and none are taken away

Subtracting on a number line

8
3
⬅️ Subtracting on a number line
①The red dot marks the number you start at
②The red dashed arc is a hop to the left, as long as the number you take away
③The −number above the arc is the amount you take away
④The green dot is where you land, and that number is the answer
⑤Subtracting moves you to the left on a number line

Addition and subtraction go together

🤝 Addition ↔ subtraction
①If 3 + 4 = 7
②then 7 − 4 = 3
③and 7 − 3 = 4 is true too
④Know one addition fact and you can write its two subtraction partners right away

Wrap-up

The minus sign
whole − part taken = what is left
The − sign means taking some away from the whole
Subtracting 0
any number − 0 = the same number
Nothing is taken away, so the number stays the same
Subtracting a number from itself
any number − the same number = 0
Take everything away and nothing is left
🎯 Remember
①Subtraction means taking some away and finding what is left
②− is read "minus"
③On a number line, you move left by the number you take away
④Subtracting 0 changes nothing; subtracting a number from itself gives 0
⑤Addition and subtraction go together

Examples and unit check

Example 1
There are 7 cookies. If you eat 2 of them, how many are left?
1
Take the 2 eaten cookies away from all 7.
2
7 − 2 = 5, so 5 are left.
▸ 5 cookies
Subtracting means taking part away from the whole.
Example 2
3 + 4 = 7. Use this to find 7 − 4.
1
Think of the addition fact 3 + 4 = 7 backward.
2
Take 4 away from 7 and 3 is left, so 7 − 4 = 3.
▸ 3
If you know an addition fact, you also know the answer to its subtraction partner.
Unit check
Which is the value of 6 − 4?
①1
②2
③3
④10
▸ ② 2
1
Take 4 away from 6.
2
6 − 4 = 2.
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addition
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Carrying and Borrowing

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