Solve for X: Finding the Number That Makes X × 100 = 511

Q: Why do I divide both sides by 100?

To solve $ ? \times 100 = 511 $, you need to isolate the unknown. Since it's multiplied by 100, you divide both sides by 100 to undo that multiplication.

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

When dividing by 100, move the decimal point 2 places to the left. So 511 ÷ 100 becomes 5.11 (the decimal moves from after the last 1 to between the 5 and first 1).

Q: What if I got 51.1 instead of 5.11?

You only moved the decimal 1 place instead of 2! Remember: dividing by 100 = moving decimal 2 places left, dividing by 10 = moving 1 place left.

Q: How can I check if 5.11 is correct?

Substitute back into the original equation: $ 5.11 \times 100 $. When you multiply by 100, move the decimal 2 places right: 5.11 becomes 511. Perfect match!

Q: Is there a shortcut for dividing by 100?

Yes! Dividing by 100 is the same as moving the decimal point 2 places to the left. It's much faster than long division for problems like this.

Division with Decimal Results

$?\times100=511$

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations

00:00 Find the unknown

00:04 Divide by the factor to find the unknown

00:14 Move the decimal point according to the number of zeros, and find the unknown

00:22 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

$?\times100=511$

Step-by-step solution

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

Step 1: Identify the equation $? \times 100 = 511$ .
Step 2: Solve for the unknown by using division.

Now, let's work through the solution:

Step 1: We start with the equation provided: $? \times 100 = 511$ .

Step 2: To isolate the unknown, divide both sides of the equation by 100.
$? = \frac{511}{100}$

Performing the division, we have:
$? = 5.11$

Therefore, the solution to the problem is $5.11$ .

Final Answer

$5.11$

Key Points to Remember

Essential concepts to master this topic

Rule: Use division to isolate the unknown variable
Technique: Divide both sides: $\frac{511}{100} = 5.11$
Check: Substitute back: $5.11 \times 100 = 511$ ✓

Common Mistakes

Avoid these frequent errors

Misplacing the decimal point in division
Don't rush through $\frac{511}{100}$ = 51.1! Moving the decimal wrong gives an answer 10 times too big. Always count decimal places carefully: dividing by 100 moves the decimal point exactly 2 places left.

Practice Quiz

Test your knowledge with interactive questions

$$ 20.1:10= $$

FAQ

Everything you need to know about this question

Why do I divide both sides by 100?

To solve $? \times 100 = 511$ , you need to isolate the unknown. Since it's multiplied by 100, you divide both sides by 100 to undo that multiplication.

How do I know where to put the decimal point?

When dividing by 100, move the decimal point 2 places to the left. So 511 ÷ 100 becomes 5.11 (the decimal moves from after the last 1 to between the 5 and first 1).

What if I got 51.1 instead of 5.11?

You only moved the decimal 1 place instead of 2! Remember: dividing by 100 = moving decimal 2 places left, dividing by 10 = moving 1 place left.

How can I check if 5.11 is correct?

Substitute back into the original equation: $5.11 \times 100$ . When you multiply by 100, move the decimal 2 places right: 5.11 becomes 511. Perfect match!

Is there a shortcut for dividing by 100?

Yes! Dividing by 100 is the same as moving the decimal point 2 places to the left. It's much faster than long division for problems like this.

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