Solve Decimal Multiplication: 0.15 × 200 Step-by-Step

Q: Why do I multiply 15 × 200 instead of 0.15 × 200 directly?

Multiplying whole numbers is easier and less error-prone! By treating 0.15 as 15, you avoid decimal confusion during calculation. Just remember to adjust for the decimal places at the end.

Q: How do I know where to put the decimal point?

Count the decimal places in your decimal number. Since $ 0.15 $ has 2 decimal places, divide your whole number result by $ 100 $ (which is $ 10^2 $).

Q: What if I get confused with the decimal placement?

Use estimation to check! $ 0.15 $ is close to $ 0.2 $, and $ 0.2 \times 200 = 40 $. So your answer should be close to 40, which makes 30 reasonable!

Q: Can I just move the decimal point instead of dividing?

Absolutely! Moving the decimal point 2 places to the left in 3000 gives you 30.00 = 30. This is the same as dividing by 100, just faster!

Q: What if my answer seems too big or too small?

Always do a reasonableness check! Since $ 0.15 $ is less than 1, multiplying by 200 should give you something less than 200. If you get 3000, that's clearly wrong!

Decimal Multiplication with Whole Numbers

$0.15\times200=$

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations

00:04 Let's solve this problem step by step.

00:08 First, we split 200 into two parts. One hundred and two. Let's tackle these one at a time.

00:24 We'll multiply each part and add them for the final answer. Keep going, you're doing great!

00:33 And there you have it, that's our solution!

Step-by-step written solution

Follow each step carefully to understand the complete solution

Understand the problem

$0.15\times200=$

Step-by-step solution

To solve this problem, we'll follow these steps:

Step 1: Convert the multiplication into a simpler operation by treating decimals appropriately.
Step 2: Perform the multiplication.
Step 3: Adjust the result for decimal placement.

Now, let's work through each step:
Step 1: We need to find the result of multiplying $0.15$ by $200$ .
Step 2: Multiply as if $0.15$ is $15$ , then apply appropriate scaling for the decimal places:
$15 \times 200 = 3000$
Step 3: Since $0.15$ has two decimal places, divide the result by $100$ :
$\frac{3000}{100} = 30$

Therefore, the solution to the problem is $30$ .

Final Answer

$30$

Key Points to Remember

Essential concepts to master this topic

Rule: Count decimal places in the decimal factor for final placement
Technique: Multiply 15 × 200 = 3000, then place decimal correctly
Check: Verify 0.15 × 200 = 30 by estimating 0.15 ≈ 0.2, so 0.2 × 200 = 40 ✓

Common Mistakes

Avoid these frequent errors

Forgetting to place the decimal point correctly
Don't just multiply 15 × 200 = 3000 and forget about decimals! This gives 3000 instead of 30, which is 100 times too large. Always count the decimal places in the original decimal (0.15 has 2 places) and divide your result by the corresponding power of 10.

Practice Quiz

Test your knowledge with interactive questions

$\text{0}.07\times10=$

FAQ

Everything you need to know about this question

Why do I multiply 15 × 200 instead of 0.15 × 200 directly?

Multiplying whole numbers is easier and less error-prone! By treating 0.15 as 15, you avoid decimal confusion during calculation. Just remember to adjust for the decimal places at the end.

How do I know where to put the decimal point?

Count the decimal places in your decimal number. Since $0.15$ has 2 decimal places, divide your whole number result by $100$ (which is $10^2$ ).

What if I get confused with the decimal placement?

Use estimation to check! $0.15$ is close to $0.2$ , and $0.2 \times 200 = 40$ . So your answer should be close to 40, which makes 30 reasonable!

Can I just move the decimal point instead of dividing?

Absolutely! Moving the decimal point 2 places to the left in 3000 gives you 30.00 = 30. This is the same as dividing by 100, just faster!

What if my answer seems too big or too small?

Always do a reasonableness check! Since $0.15$ is less than 1, multiplying by 200 should give you something less than 200. If you get 3000, that's clearly wrong!

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