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FractionsArithmeticElementary schoolabout 0:51

Calculate 7/8 + 8/7: animated lesson

A narrated, step-by-step fractions video lesson with captions. Final answer: 113/56.

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Video with a synthetic English voice and captions. Pick another language for subtitles in that language, or open the interactive version.

Video narrated by a synthetic voice (Piper TTS, en_US-ljspeech-high voice (LJ Speech dataset, public domain)); the steps come from our maths engine and the answer was checked independently. Download MP4 (0.3 MB) · Captions (WebVTT)

Steps on screen

1. The problem
Worked example
7/8 + 8/7
2. Step by step
1. $\frac{7}{8} + \frac{8}{7} = \frac{49}{56} + \frac{64}{56}$
  Rewrite both fractions with the least common denominator
2. $\frac{49 + 64}{56} = \frac{113}{56}$
  Add the numerators and keep the denominator
3. $\frac{113}{56} = 2\tfrac{1}{56}$
  Final answer in lowest terms
3. The answer
$\frac{113}{56}$
7/8 + 8/7 = 113/56
4. Check
- Decimal check: 113/56 ≈ 2.017857143
- As a mixed number: 2 1/56

Transcript

The problem. Here is the problem: 7 over 8 plus 8 over 7. Exact arithmetic with fractions (results kept in lowest terms).

Step by step. Rewrite both fractions with the least common denominator. The LCD of 8 and 7 is 56. Add the numerators and keep the denominator. Final answer in lowest terms.

The answer. So the answer is 113 over 56. Fractions are combined over a common denominator for addition and subtraction, multiplied straight across, and divided by multiplying by the reciprocal. The result is reduced by the greatest common factor.

Check. Decimal check: 113 over 56 approximately 2.017857143. As a mixed number: 2 1 over 56.

About fractions

Add, subtract, multiply and divide fractions, finding common denominators and simplifying the result.

Calculate 7/8 + 8/7: Fractions Step-by-Step Lesson