Solve: 4 × 3⅞ Mixed Number Multiplication Problem

Mixed Number Multiplication with Improper Fractions

4×379= 4\times3\frac{7}{9}=

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Solve
00:04 First convert mixed fraction to fraction
00:20 Raise the multiplication to the numerator
00:27 Calculate the multiplication
00:32 Now convert to mixed fraction
00:37 Break down 136 into 135 plus 1
00:45 Break down the fraction into whole fraction and remainder
00:53 Convert whole fraction to whole number, and combine with mixed fraction
01:01 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

4×379= 4\times3\frac{7}{9}=

2

Step-by-step solution

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

  • Step 1: Convert the mixed number 3793\frac{7}{9} to an improper fraction.
  • Step 2: Multiply the improper fraction by the whole number 4.
  • Step 3: Simplify the result back to a mixed number.

Now, let's work through each step:
Step 1: Convert 3793\frac{7}{9} to an improper fraction:
The denominator is 9. Multiply the whole number 3 by 9 and add the numerator 7:
3×9+7=27+7=343 \times 9 + 7 = 27 + 7 = 34.
So, 379=3493\frac{7}{9} = \frac{34}{9}.

Step 2: Multiply 349\frac{34}{9} by 4:
4×349=4×349=1369 4 \times \frac{34}{9} = \frac{4 \times 34}{9} = \frac{136}{9} .

Step 3: Simplify 1369\frac{136}{9} to a mixed number:
Divide 136 by 9. The quotient is 15, and the remainder is 1. Thus, 1369=1519\frac{136}{9} = 15\frac{1}{9}.

Therefore, the solution to the problem is 1519 15\frac{1}{9} .

3

Final Answer

1519 15\frac{1}{9}

Key Points to Remember

Essential concepts to master this topic
  • Rule: Convert mixed numbers to improper fractions before multiplying
  • Technique: For 379 3\frac{7}{9} , calculate 3×9+7 = 34, making 349 \frac{34}{9}
  • Check: Convert final answer back: 1369 \frac{136}{9} = 15 remainder 1 = 1519 15\frac{1}{9}

Common Mistakes

Avoid these frequent errors
  • Multiplying whole number and fraction parts separately
    Don't multiply 4×3 = 12 and 4×79 \frac{7}{9} separately, then add them together = wrong answer! This ignores the fact that the mixed number represents one complete value. Always convert the mixed number to an improper fraction first, then multiply.

Practice Quiz

Test your knowledge with interactive questions

\( 5:\frac{2}{5}= \)

FAQ

Everything you need to know about this question

Why can't I just multiply the whole number parts and fraction parts separately?

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Because a mixed number like 379 3\frac{7}{9} represents one complete number, not two separate parts. Multiplying separately would give you 12 + 289 \frac{28}{9} = 1519 15\frac{1}{9} , which happens to work here but fails with other operations like division.

How do I convert a mixed number to an improper fraction quickly?

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Use the formula: multiply the whole number by the denominator, then add the numerator. For 379 3\frac{7}{9} : (3×9) + 7 = 27 + 7 = 34, so it becomes 349 \frac{34}{9} .

When do I know to convert back to a mixed number?

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Convert back when your final answer is an improper fraction (numerator larger than denominator). Divide the numerator by denominator: quotient becomes the whole number, remainder becomes the new numerator.

What if I get confused with the division step at the end?

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Remember: 1369 \frac{136}{9} means "136 ÷ 9". Use long division or think "how many 9s fit into 136?" Answer: 15 times with 1 left over, so 1519 15\frac{1}{9} .

Can I leave my answer as an improper fraction instead?

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Usually mixed numbers are preferred for final answers because they're easier to understand. However, check your teacher's preference - some contexts prefer improper fractions!

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