Solve Mixed Number Addition: 2½ + 3⅐ Step-by-Step

Mixed Number Addition with Different Denominators

212+317= 2\frac{1}{2}+3\frac{1}{7}=

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:04 Let's solve this problem together.
00:08 First, change any mixed numbers into improper fractions.
00:49 Next, multiply each fraction by the second denominator to get a common denominator.
00:57 Now, work out the multiplication results.
01:09 Add the fractions together using the common denominator.
01:21 Alright, convert your result back to a mixed number.
01:28 Break 79 into seventy plus nine to make it easier.
01:39 Let's divide the fraction into a whole number and remainder.
01:46 Turn the whole fraction into a whole number, then combine it with the mixed number.
01:52 And that’s how we find the solution!

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

212+317= 2\frac{1}{2}+3\frac{1}{7}=

2

Step-by-step solution

To solve the addition of 212+3172\frac{1}{2} + 3\frac{1}{7}, we will follow these steps:

  • Convert each mixed number to an improper fraction.
  • Find a common denominator for the fractions.
  • Add the fractions together.
  • Convert the resulting improper fraction back to a mixed number.

Now, let's perform the calculations:
Step 1: Convert to improper fractions.
2122\frac{1}{2} becomes 52\frac{5}{2} because (2×2)+1=5(2 \times 2) + 1 = 5.
3173\frac{1}{7} becomes 227\frac{22}{7} because (3×7)+1=22(3 \times 7) + 1 = 22.

Step 2: Find a common denominator.
The least common denominator of 2 and 7 is 14. We convert 52\frac{5}{2} and 227\frac{22}{7} to have this common denominator:
52=3514\frac{5}{2} = \frac{35}{14} (because 5×7=355 \times 7 = 35)
227=4414\frac{22}{7} = \frac{44}{14} (because 22×2=4422 \times 2 = 44)

Step 3: Add the resulting fractions.
3514+4414=7914\frac{35}{14} + \frac{44}{14} = \frac{79}{14}

Step 4: Convert the improper fraction back to a mixed number.
7914\frac{79}{14} can be expressed as 59145\frac{9}{14} because 79 divided by 14 is 5 with a remainder of 9.

Therefore, the solution to the problem is 59145\frac{9}{14}.

3

Final Answer

5914 5\frac{9}{14}

Key Points to Remember

Essential concepts to master this topic
  • Method: Convert mixed numbers to improper fractions before adding
  • Technique: Find LCD of 2 and 7 which is 14
  • Check: Verify 5914 5\frac{9}{14} equals original sum ✓

Common Mistakes

Avoid these frequent errors
  • Adding whole numbers and fractions separately without common denominators
    Don't just add 2 + 3 = 5 and ½ + ⅐ = wrong fraction! This ignores that ½ and ⅐ have different denominators and can't be directly added. Always convert to improper fractions first, find the LCD, then add.

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 add the whole numbers and fractions separately?

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You can add whole numbers separately, but the fractions need a common denominator first! 12+17 \frac{1}{2} + \frac{1}{7} requires converting both to fourteenths before adding.

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

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Multiply the whole number by the denominator, then add the numerator. For 212 2\frac{1}{2} : (2 × 2) + 1 = 5, so it becomes 52 \frac{5}{2} .

What's the easiest way to find the LCD of 2 and 7?

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Since 2 and 7 are both prime numbers, their LCD is simply their product: 2 × 7 = 14. When denominators share no common factors, multiply them together!

How do I convert the improper fraction back to a mixed number?

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Divide the numerator by the denominator. For 7914 \frac{79}{14} :

  • 79 ÷ 14 = 5 remainder 9
  • So the answer is 5914 5\frac{9}{14}

Do I need to simplify the final fraction?

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Yes, always check! In this case, 914 \frac{9}{14} cannot be simplified further since 9 and 14 share no common factors other than 1.

Can I use decimals instead of fractions?

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While possible, it's not recommended here because 17 \frac{1}{7} creates a repeating decimal (0.142857...), making the calculation messy. Stick with fractions for exact answers!

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