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Order of operationsArithmeticElementary schoolabout 0:52

Evaluate 18 + (10 - 1) / 9 - 5: animated lesson

A narrated, step-by-step order of operations video lesson with captions. Final answer: 14.

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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
18 + (10 - 1) / 9 - 5
2. Steps, part 1
1. $10 - 1 = 9$
  Subtract the whole numbers
2. $9 \div 9 = 9 \times \frac{1}{9}$
  Dividing by a fraction means multiplying by its reciprocal
3. $9 \times \frac{1}{9} = \frac{9 \times 1}{1 \times 9} = \frac{9}{9}$
  Multiply numerators and multiply denominators
4. $\frac{9}{9} = 1$
  Simplify
3. Steps, part 2
1. $18 + 1 = 19$
  Add the whole numbers
2. $19 - 5 = 14$
  Subtract the whole numbers
3. $14$
  Final answer in lowest terms
4. The answer
$14$
18 + (10 - 1) / 9 - 5 = 14
5. Check
- Decimal check: 14 ≈ 14

Transcript

The problem. Here is the problem: 18 plus (10 minus 1) / 9 minus 5. Exact arithmetic with fractions (results kept in lowest terms).

Steps, part 1. Subtract the whole numbers. Dividing by a fraction means multiplying by its reciprocal. Multiply numerators and multiply denominators. Simplify. Divide numerator and denominator by their GCF, 9.

Steps, part 2. Add the whole numbers. Subtract the whole numbers. Final answer in lowest terms.

The answer. So the answer is 14. 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: 14 approximately 14.

About order of operations

Evaluate expressions with brackets, powers, multiplication, division, addition and subtraction in the right order.

Evaluate 18 + (10 - 1) / 9 - 5: Animated Step-by-Step Lesson