Solve the Multiplication Equation: Finding the Number That Makes ?×10=45

Q: Why do I divide by 10 instead of multiply?

Because division is the opposite of multiplication! If something is multiplied by 10, you need to divide by 10 to "undo" it and isolate the unknown number.

Q: How do I divide 45 by 10 quickly?

When dividing by 10, simply move the decimal point one place to the left! So 45.0 ÷ 10 = 4.5. This trick works for any number divided by 10.

Q: What if I get a decimal answer - is that wrong?

Decimal answers are perfectly correct! Many multiplication equations have decimal solutions. Just make sure to check your work by multiplying back.

Q: Can I check my answer a different way?

Yes! You can also think: "What number times 10 equals 45?" Count by 10s: 10, 20, 30, 40... then 45 is halfway between 40 and 50, so the answer is 4.5.

Q: What if the equation was ? × 100 = 45 instead?

Same process! Divide both sides by 100: $ \frac{45}{100} = 0.45 $. The method stays the same - always divide by whatever number is being multiplied.

Division Equations with Decimal Results

$?\times10=45$

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations

00:00 Find the unknown

00:05 Divide by the factor to find the unknown

00:16 Move the decimal point according to the number of zeros, and find the unknown

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

$?\times10=45$

Step-by-step solution

To solve the problem $? \times 10 = 45$ , we can use the following steps:

Step 1: Understand the equation $(? \times 10 = 45)$ .
Step 2: Rearrange the equation to solve for the unknown: $? = \frac{45}{10}$ .
Step 3: Perform the division operation: $\frac{45}{10} = 4.5$ .

We divide 45 by 10 to find that the missing number is 4.5. Therefore, $4.5 \times 10 = 45$ .

Thus, the missing number in the equation is $\boxed{4.5}$ .

From the given choices, the correct answer is $\boxed{4.5}$ , which corresponds to choice 3.

Final Answer

$4.5$

Key Points to Remember

Essential concepts to master this topic

Inverse Operations: Solve $? \times 10 = 45$ by dividing both sides by 10
Division Method: Calculate $\frac{45}{10} = 4.5$ to find the missing number
Verification: Check by multiplying: $4.5 \times 10 = 45$ ✓

Common Mistakes

Avoid these frequent errors

Adding or subtracting instead of dividing
Don't try 45 + 10 = 55 or 45 - 10 = 35! These give completely wrong answers because multiplication requires division to undo it. Always use the inverse operation: if something is multiplied by 10, divide by 10 to solve.

Practice Quiz

Test your knowledge with interactive questions

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

FAQ

Everything you need to know about this question

Why do I divide by 10 instead of multiply?

Because division is the opposite of multiplication! If something is multiplied by 10, you need to divide by 10 to "undo" it and isolate the unknown number.

How do I divide 45 by 10 quickly?

When dividing by 10, simply move the decimal point one place to the left! So 45.0 ÷ 10 = 4.5. This trick works for any number divided by 10.

What if I get a decimal answer - is that wrong?

Decimal answers are perfectly correct! Many multiplication equations have decimal solutions. Just make sure to check your work by multiplying back.

Can I check my answer a different way?

Yes! You can also think: "What number times 10 equals 45?" Count by 10s: 10, 20, 30, 40... then 45 is halfway between 40 and 50, so the answer is 4.5.

What if the equation was ? × 100 = 45 instead?

Same process! Divide both sides by 100: $\frac{45}{100} = 0.45$ . The method stays the same - always divide by whatever number is being multiplied.

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