Solve Decimal Division: 0.121 ÷ 0.1 Step-by-Step

Q: Why do we multiply both numbers by 10?

Multiplying both the dividend and divisor by the same number doesn't change the answer! It's like simplifying a fraction - $ \frac{4}{8} = \frac{2}{4} $ when we divide both by 2.

Q: How do I know which power of 10 to use?

Look at the divisor! Count the decimal places in 0.1 (one place), so multiply by $ 10^1 = 10 $. For 0.01, you'd use $ 10^2 = 100 $.

Q: Can I just move the decimal points instead?

Yes! Moving decimal points is the same as multiplying by powers of 10. Just remember to move them the same number of places in both numbers.

Q: What if I get confused about which direction to move decimals?

Focus on making the divisor a whole number first. Move its decimal point right until it's whole, then move the dividend's decimal point the same number of places right.

Q: Why is the answer bigger than what we started with?

When you divide by a number less than 1 (like 0.1), the answer gets bigger! Think: How many 0.1s fit into 0.121? More than one, so the answer exceeds 1.

Decimal Division with Eliminating Decimal Points

$0.121:0.1=$

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations

00:00 Solve

00:04 Let's multiply each factor by 10, to make it easier to divide

00:18 Let's divide between the new numbers and calculate the quotient

00:22 Any number divided by 1 is always equal to itself

00:27 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

$0.121:0.1=$

Step-by-step solution

The task is to divide $0.121$ by $0.1$ .

To simplify this calculation, we can eliminate the decimal in the divisor:

Multiply both the dividend and the divisor by 10:

$0.121 \times 10 = 1.21$

$0.1 \times 10 = 1$

Now we divide $1.21$ by $1$ , which simplifies to:

$1.21 \div 1 = 1.21$

Thus, the answer to the division $0.121 \div 0.1$ is $1.21$ .

Matching this result with the provided choices, the correct answer is:

$1.21$ , which corresponds to choice 3.

Therefore, the solution to the problem is $1.21$ .

Final Answer

$1.21$

Key Points to Remember

Essential concepts to master this topic

Rule: Multiply both dividend and divisor by same power of 10
Technique: Move decimal point: $0.121 \div 0.1$ becomes $1.21 \div 1$
Check: Verify $1.21 \times 0.1 = 0.121$ matches original dividend ✓

Common Mistakes

Avoid these frequent errors

Only moving decimal point in one number
Don't move the decimal point in just the divisor 0.1 to make it 1 while leaving 0.121 unchanged = wrong division! This changes the value completely. Always multiply both numbers by the same power of 10 to maintain equality.

Practice Quiz

Test your knowledge with interactive questions

$$ 0.121:0.1= $$

FAQ

Everything you need to know about this question

Why do we multiply both numbers by 10?

Multiplying both the dividend and divisor by the same number doesn't change the answer! It's like simplifying a fraction - $\frac{4}{8} = \frac{2}{4}$ when we divide both by 2.

How do I know which power of 10 to use?

Look at the divisor! Count the decimal places in 0.1 (one place), so multiply by $10^1 = 10$ . For 0.01, you'd use $10^2 = 100$ .

Can I just move the decimal points instead?

Yes! Moving decimal points is the same as multiplying by powers of 10. Just remember to move them the same number of places in both numbers.

What if I get confused about which direction to move decimals?

Focus on making the divisor a whole number first. Move its decimal point right until it's whole, then move the dividend's decimal point the same number of places right.

Why is the answer bigger than what we started with?

When you divide by a number less than 1 (like 0.1), the answer gets bigger! Think: How many 0.1s fit into 0.121? More than one, so the answer exceeds 1.

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