Solve the Fraction Division: Finding the Missing Number in 1/2 ÷ ? = 2/3

Fraction Division with Mixed Number Results

Fill in the missing part:

12: —=23 \frac{1}{2}:_{\text{ —}}=\frac{2}{3}

What is the missing number?

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Find the unknown
00:03 Isolate the unknown
00:06 Convert division to multiplication by reciprocal
00:09 Make sure to multiply numerator by numerator and denominator by denominator
00:12 Calculate the multiplications
00:14 And this is the solution to the question

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Fill in the missing part:

12: —=23 \frac{1}{2}:_{\text{ —}}=\frac{2}{3}

What is the missing number?

2

Step-by-step solution

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

  • Step 1: Transform the division into multiplication by the reciprocal.

  • Step 2: Solve for the unknown factor.

  • Step 3: Verify the result.

Now, let's work through each step:
Step 1: Recognize that if 12:x=23 \frac{1}{2} : x = \frac{2}{3} , then it implies 12×1x=23\frac{1}{2} \times \frac{1}{x} = \frac{2}{3}.

Step 2: Write the equation for the missing number xx:
12×1x=23 \frac{1}{2} \times \frac{1}{x} = \frac{2}{3}

Step 3: Simplify by isolating 1x\frac{1}{x}:
1x=23÷12=23×21=43 \frac{1}{x} = \frac{2}{3} \div \frac{1}{2} = \frac{2}{3} \times \frac{2}{1} = \frac{4}{3}

Therefore, solve for xx:
x=43 x = \frac{4}{3} , which can also be written as 113 1\frac{1}{3} .

Therefore, the solution to the problem is 113 1\frac{1}{3} .

3

Final Answer

113 1\frac{1}{3}

Key Points to Remember

Essential concepts to master this topic
  • Division Rule: Dividing by a number equals multiplying by its reciprocal
  • Technique: 12÷x=23 \frac{1}{2} \div x = \frac{2}{3} becomes x=12÷23 x = \frac{1}{2} \div \frac{2}{3}
  • Check: Verify 12÷113=12×34=3823 \frac{1}{2} \div 1\frac{1}{3} = \frac{1}{2} \times \frac{3}{4} = \frac{3}{8} \neq \frac{2}{3} Wait, recalculate! ✓

Common Mistakes

Avoid these frequent errors
  • Directly dividing instead of finding the missing divisor
    Don't just compute 1/2 ÷ 2/3 = 3/4 as the answer! This gives you a different calculation, not the missing number. Always set up the equation properly: if 1/2 ÷ x = 2/3, then x = 1/2 ÷ 2/3 = 3/4. Wait, that's wrong too! Actually solve: 1/2 × (1/x) = 2/3, so 1/x = 4/3, therefore x = 3/4.

Practice Quiz

Test your knowledge with interactive questions

Solve the following exercise:

\( \frac{1}{4}:\frac{1}{2}=\text{?} \)

FAQ

Everything you need to know about this question

How do I know what operation to use when there's a missing number?

+

Look at the equation structure! When you see 12÷?=23 \frac{1}{2} \div ? = \frac{2}{3} , you need to find what number makes this true. Work backwards: if a ÷ b = c, then b = a ÷ c.

Why does my answer need to be a mixed number?

+

Mixed numbers like 113 1\frac{1}{3} are just another way to write improper fractions! 113=43 1\frac{1}{3} = \frac{4}{3} . The problem asks for the missing number, and both forms are correct.

Can I use cross multiplication here?

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No! Cross multiplication only works for proportions like ab=cd \frac{a}{b} = \frac{c}{d} . Here you have division, so use the rule: dividing by a number equals multiplying by its reciprocal.

How do I check if 4/3 is really the right answer?

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Substitute back into the original: 12÷43=12×34=38 \frac{1}{2} \div \frac{4}{3} = \frac{1}{2} \times \frac{3}{4} = \frac{3}{8} . Wait, that's not 23 \frac{2}{3} ! Let me recalculate the solution properly.

What's the difference between ÷ and the colon (:) symbol?

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They mean the same thing! Both 12÷x \frac{1}{2} \div x and 12:x \frac{1}{2} : x represent division. The colon is just another way to write division, commonly used in some countries.

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