Solve the Arithmetic Equation: 90 - 2 + 9 - 8

Q: Why can't I just add all the positive numbers and subtract all the negative numbers?

While it works for this problem, it's not always correct! The order matters in arithmetic. For example, 10-8+2 ≠ (10+2)-8 in some contexts. Always follow left-to-right rule to build good habits.

Q: What if I accidentally calculate 90+9-2-8 instead?

You'd get $ 90+9-2-8 = 89 $, which happens to be the same answer! But this rearrangement doesn't always work. Stick to the original order to avoid mistakes in trickier problems.

Q: Is there a faster way to solve this?

You could think of it as $ 90 + (-2) + 9 + (-8) $ and group: $ 90 + 9 + (-2) + (-8) = 99 - 10 = 89 $. But left-to-right is safer and more reliable!

Q: How do I avoid making calculation errors?

Write each step clearly:Step 1: $ 90 - 2 = 88 $Step 2: $ 88 + 9 = 97 $Step 3: $ 97 - 8 = 89 $Double-check each calculation before moving to the next step.

Q: What's the most important rule to remember?

When you have only addition and subtraction, work from left to right since they have equal precedence. This is different from multiplication and division, which come before addition and subtraction!

Order of Operations with Mixed Addition and Subtraction

$90-2+9-8=\text{ ?}$

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations

00:00 Solve the following expression

00:03 Proceed using the correct order of operations, from left to right

00:07 Each time solve one operation and then continue

00:12 Given that all operations are only addition/subtraction

00:16 We'll use the commutative law and solve this operation first

00:26 This is the solution

Step-by-step written solution

Follow each step carefully to understand the complete solution

Understand the problem

$90-2+9-8=\text{ ?}$

Step-by-step solution

According to the order of operations, we will solve the exercise from left to right since the only operations in it are addition and subtraction:

$90-2=88$

$88+9=97$

$97-8=89$

Final Answer

Key Points to Remember

Essential concepts to master this topic

Rule: Addition and subtraction have equal precedence, work left to right
Technique: Calculate step by step: 90-2=88, then 88+9=97, then 97-8=89
Check: Verify by reworking: (90-2)+(9-8) = 88+1 = 89 ✓

Common Mistakes

Avoid these frequent errors

Grouping addition and subtraction separately
Don't calculate (90+9)-(2+8) = 99-10 = 89! This changes the order and can give wrong answers in other problems. Always work left to right when operations have equal precedence.

Practice Quiz

Test your knowledge with interactive questions

$$ 8 - 2 + 6 = $$

FAQ

Everything you need to know about this question

Why can't I just add all the positive numbers and subtract all the negative numbers?

While it works for this problem, it's not always correct! The order matters in arithmetic. For example, 10-8+2 ≠ (10+2)-8 in some contexts. Always follow left-to-right rule to build good habits.

What if I accidentally calculate 90+9-2-8 instead?

You'd get $90+9-2-8 = 89$ , which happens to be the same answer! But this rearrangement doesn't always work. Stick to the original order to avoid mistakes in trickier problems.

Is there a faster way to solve this?

You could think of it as $90 + (-2) + 9 + (-8)$ and group: $90 + 9 + (-2) + (-8) = 99 - 10 = 89$ . But left-to-right is safer and more reliable!

How do I avoid making calculation errors?

Write each step clearly:

Step 1: $90 - 2 = 88$
Step 2: $88 + 9 = 97$
Step 3: $97 - 8 = 89$

Double-check each calculation before moving to the next step.

What's the most important rule to remember?

When you have only addition and subtraction, work from left to right since they have equal precedence. This is different from multiplication and division, which come before addition and subtraction!

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Solve the Arithmetic Equation: 90 - 2 + 9 - 8

Order of Operations with Mixed Addition and Subtraction

❤️ Continue Your Math Journey!

Step-by-step video solution

Step-by-step written solution

Understand the problem

Step-by-step solution

Final Answer

Key Points to Remember

Common Mistakes

Practice Quiz

FAQ

Why can't I just add all the positive numbers and subtract all the negative numbers?

What if I accidentally calculate 90+9-2-8 instead?

Is there a faster way to solve this?

How do I avoid making calculation errors?

What's the most important rule to remember?

🌟 Unlock Your Math Potential

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