Solve Sequential Subtraction: 12 - 5 - 2 Step by Step

Q: Why can't I subtract 5 - 2 first and then subtract that from 12?

Because subtraction is not associative! The expression $12 - 5 - 2$ means $(12 - 5) - 2$, not $12 - (5 - 2)$. Always work left to right with subtraction.

Q: What if I accidentally get 9 as my answer?

You probably calculated $12 - (5 - 2) = 12 - 3 = 9$. Remember: without parentheses, work left to right. The correct calculation is $(12 - 5) - 2 = 7 - 2 = 5$.

Q: Is there a way to check my answer besides working backwards?

Yes! You can think of it as: "What number plus 5 plus 2 equals 12?" Since $5 + 5 + 2 = 12$, your answer of 5 is correct!

Q: Does the order matter in subtraction like it does in addition?

Yes, order matters a lot! Unlike addition where $3 + 4 = 4 + 3$, subtraction gives different results: $12 - 5 ≠ 5 - 12$. Always follow left-to-right order.

Q: How is this different from 12 - (5 - 2)?

Parentheses change everything! $12 - (5 - 2) = 12 - 3 = 9$, but $12 - 5 - 2 = 7 - 2 = 5$. No parentheses means work left to right!

Sequential Subtraction with Multiple Terms

$12 - 5 - 2 =$

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Understand the problem

$12 - 5 - 2 =$

Step-by-step solution

First, subtract the second number from the first:

$12 - 5 = 7$

Then, subtract the third number from the result:

$7 - 2 = 5$

So, $12 - 5 - 2 = 5$

Final Answer

$5$

Key Points to Remember

Essential concepts to master this topic

Order Rule: Work from left to right with subtraction operations
Technique: First calculate 12 - 5 = 7, then 7 - 2 = 5
Check: Verify by adding back: 5 + 2 + 5 = 12 ✓

Common Mistakes

Avoid these frequent errors

Subtracting from right to left or grouping incorrectly
Don't calculate 5 - 2 = 3 first, then 12 - 3 = 9! This ignores order of operations and gives wrong answers. Always work left to right: 12 - 5 first, then subtract 2 from that result.

Practice Quiz

Test your knowledge with interactive questions

$$ 8 - 2 + 6 = $$

FAQ

Everything you need to know about this question

Why can't I subtract 5 - 2 first and then subtract that from 12?

Because subtraction is not associative! The expression $12 - 5 - 2$ means $(12 - 5) - 2$ , not $12 - (5 - 2)$ . Always work left to right with subtraction.

What if I accidentally get 9 as my answer?

You probably calculated $12 - (5 - 2) = 12 - 3 = 9$ . Remember: without parentheses, work left to right. The correct calculation is $(12 - 5) - 2 = 7 - 2 = 5$ .

Is there a way to check my answer besides working backwards?

Yes! You can think of it as: "What number plus 5 plus 2 equals 12?" Since $5 + 5 + 2 = 12$ , your answer of 5 is correct!

Does the order matter in subtraction like it does in addition?

Yes, order matters a lot! Unlike addition where $3 + 4 = 4 + 3$ , subtraction gives different results: $12 - 5 ≠ 5 - 12$ . Always follow left-to-right order.

How is this different from 12 - (5 - 2)?

Parentheses change everything! $12 - (5 - 2) = 12 - 3 = 9$ , but $12 - 5 - 2 = 7 - 2 = 5$ . No parentheses means work left to right!

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