Solve Addition: (-202) + (-8.7) Step by Step

Q: Why is (-202) + (-8.7) the same as -202 - 8.7?

The rule $ +(-x) = -x $ means adding a negative is the same as subtracting. So (-202) + (-8.7) becomes -202 - 8.7, which is easier to calculate!

Q: How do I know the answer should be negative?

When you add two negative numbers, you're moving further left on the number line. Starting at -202 and moving 8.7 more steps left gives you -210.7.

Q: Do I need to line up the decimal points?

Yes! When adding -202.0 + (-8.7), align the decimal points:-202.0+ (-8.7)= -210.7

Q: Can I just add 202 + 8.7 and then make it negative?

Absolutely! Since both numbers are negative, you can add their absolute values (202 + 8.7 = 210.7) and then put a negative sign: -210.7.

Negative Number Addition with Decimal Numbers

Solve the following problem:

$(-202)+(-8.7)=$

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations

00:06 Let's solve this problem.

00:09 We need to find the point at negative two hundred two on the number line.

00:14 Remember, positive times negative is always negative. So, we subtract.

00:19 To subtract, move to the left, or negatively, on the number line.

00:24 And that's how we find the solution to this problem.

Step-by-step written solution

Follow each step carefully to understand the complete solution

Understand the problem

Solve the following problem:

$(-202)+(-8.7)=$

Step-by-step solution

Let's remember the rule:

$+(-x)=-x$

Now let's write the exercise in the appropriate form:

$-202-8.7=$

We'll position -202 on the number line, and we move 8.7 steps to the left:

Therefore, the result is:

$-202-8.7=-210.7$

Final Answer

$-210.7$

Key Points to Remember

Essential concepts to master this topic

Rule: Adding two negative numbers always gives a more negative result
Technique: Convert (+)(-8.7) to -8.7, then calculate -202 + (-8.7) = -210.7
Check: Both numbers negative means sum is negative: -202 - 8.7 = -210.7 ✓

Common Mistakes

Avoid these frequent errors

Making the final answer positive
Don't think (-202) + (-8.7) = 210.7 because you're adding! This ignores the negative signs completely. When adding two negative numbers, the result is always MORE negative, not positive. Always keep the negative sign and add the absolute values.

Practice Quiz

Test your knowledge with interactive questions

$$ -5-(-2)= $$

FAQ

Everything you need to know about this question

Why is (-202) + (-8.7) the same as -202 - 8.7?

The rule $+(-x) = -x$ means adding a negative is the same as subtracting. So (-202) + (-8.7) becomes -202 - 8.7, which is easier to calculate!

How do I know the answer should be negative?

When you add two negative numbers, you're moving further left on the number line. Starting at -202 and moving 8.7 more steps left gives you -210.7.

What if I accidentally made it positive?

Check your logic: you started with -202 (already negative) and added another negative number (-8.7). This should make the result more negative, not positive!

Do I need to line up the decimal points?

Yes! When adding -202.0 + (-8.7), align the decimal points:

-202.0
+ (-8.7)
= -210.7

Can I just add 202 + 8.7 and then make it negative?

Absolutely! Since both numbers are negative, you can add their absolute values (202 + 8.7 = 210.7) and then put a negative sign: -210.7.

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