Subtract
Grade 4 students learn subtraction as a take-away operation in Saxon Math Intermediate 4 Chapter 1. Subtraction separates one group into two groups; the result is how many remain. Carlos had 15 stickers, used 7, so 15 − 7 = 8 stickers remain. Students also learn subtraction as the inverse of addition: the fact family relationship means 15 − 7 = 8 can be checked by 8 + 7 = 15. Numbers must be in the correct order—always start with the total and subtract the smaller part.
Key Concepts
Property When we subtract, we separate one group into two groups. To take away two from six, we subtract. $$6 2 = 4$$.
Example For $14 8 = 6$, you can check your answer by adding up: $6 + 8 = 14$. For $15 7 = 8$, you can check with $8 + 7 = 15$.
Explanation Think of subtraction as the 'take away' game. You start with a whole group, like six cookies, and separate it by taking some away. It is the opposite of addition, so you can check your answer by adding back what you took away to see if you get the original amount!
Common Questions
What is subtraction?
Subtraction is a take-away operation that separates a group into two parts. You start with the total (the whole), remove a portion, and find what remains. The result is called the difference.
How do you check a subtraction answer using addition?
Add the difference back to the number you subtracted. The result should equal the starting total. For 15 − 7 = 8: verify by checking 8 + 7 = 15.
What is a fact family in subtraction?
A fact family is a set of related addition and subtraction equations using the same three numbers. For 8, 7, and 15: 8 + 7 = 15, 7 + 8 = 15, 15 − 7 = 8, 15 − 8 = 7.
What is the most common mistake when setting up a subtraction problem?
Putting the numbers in the wrong order. Subtraction is not commutative—15 − 7 is not the same as 7 − 15. Always put the larger total first, then subtract the smaller part.
What clue words in word problems signal subtraction?
Clue words include gave away, used, ate, lost, spent, removed, how many are left, how many remain, and how many fewer. These all indicate that a part is being removed from a whole.
How are addition and subtraction related?
They are inverse operations—each undoes the other. If you know any addition fact (e.g., 6 + 8 = 14), you automatically know two subtraction facts: 14 − 6 = 8 and 14 − 8 = 6.