Solve: Place the Decimal Point in 0.05 × 0.8 = 004

Q: Why do I need to count decimal places at all?

When multiplying decimals, the total decimal places in your answer must equal the sum of decimal places in both factors. This rule ensures your decimal point is in the correct position!

Q: What if my answer has fewer digits than decimal places needed?

Add zeros to the left of your number! For example, if you need 3 decimal places but get 40, write it as $ 0.040 $ by adding a zero before the 4.

Q: Can I just estimate where the decimal should go?

Never guess! Always use the counting rule. $ 0.05 \times 0.8 $ is close to $ 0 \times 1 = 0 $, so your answer should be small like $ 0.040 $.

Q: Do trailing zeros matter in my final answer?

For exact calculations, yes! $ 0.040 $ shows you followed the decimal place rule correctly. In some contexts, you can simplify to $ 0.04 $.

Q: What's the easiest way to remember this rule?

Think: "Add the decimal places, then place the point!" Count places in both numbers, add them together, then count that many places from the right in your answer.

Decimal Multiplication with Point Placement

Given the following exercise, find the correct place of the decimal point:

$0.05\times0.8=004$

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations

00:00 Place the decimal point

00:03 Count the total number of digits after the decimal point

00:07 According to this sum, we'll place the decimal point in the solution

00:13 We'll move the decimal point by the sum of digits

00:20 And this is the solution to the question

Step-by-step written solution

Follow each step carefully to understand the complete solution

Understand the problem

Given the following exercise, find the correct place of the decimal point:

$0.05\times0.8=004$

Step-by-step solution

To solve for the correct placement of the decimal point in the product of $0.05 \times 0.8$ , follow these steps:

Step 1: Convert the multiplication to a format without decimal points by treating the numbers as whole numbers. Multiply $5$ by $8$ to get $40$ .
Step 2: Count the total number of decimal places in the two factors. $0.05$ has 2 decimal places, and $0.8$ has 1 decimal place, summing it up to a total of 3 decimal places.
Step 3: Position the decimal point in $40$ to achieve 3 decimal places, making it $0.040$ .

Thus, the product of $0.05$ and $0.8$ with the decimal point correctly placed is $0.040$ .

Final Answer

$0.040$

Key Points to Remember

Essential concepts to master this topic

Rule: Total decimal places equals sum of both factors' places
Technique: Multiply 5 × 8 = 40, then place 3 decimal places
Check: Count places: 0.05 (2) + 0.8 (1) = 3 total ✓

Common Mistakes

Avoid these frequent errors

Only counting visible decimal places
Don't count just the digits after the decimal = wrong placement! 0.8 looks like 1 place but is really 1 place, while 0.05 is 2 places. Always count every digit position after the decimal point in each factor.

Practice Quiz

Test your knowledge with interactive questions

$0.1 \times 4.35 =$

FAQ

Everything you need to know about this question

Why do I need to count decimal places at all?

When multiplying decimals, the total decimal places in your answer must equal the sum of decimal places in both factors. This rule ensures your decimal point is in the correct position!

What if my answer has fewer digits than decimal places needed?

Add zeros to the left of your number! For example, if you need 3 decimal places but get 40, write it as $0.040$ by adding a zero before the 4.

Can I just estimate where the decimal should go?

Never guess! Always use the counting rule. $0.05 \times 0.8$ is close to $0 \times 1 = 0$ , so your answer should be small like $0.040$ .

Do trailing zeros matter in my final answer?

For exact calculations, yes! $0.040$ shows you followed the decimal place rule correctly. In some contexts, you can simplify to $0.04$ .

What's the easiest way to remember this rule?

Think: "Add the decimal places, then place the point!" Count places in both numbers, add them together, then count that many places from the right in your answer.

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