Simple and Decimal Fractions
Competitive Mathematics · Number System
In daily life — half a kilo, a quarter of a litre, ₹12.50 — we use fractions and decimals all the time. In exams they appear on their own and inside almost every other chapter (percentage, interest, average). Here you will learn what a fraction is, how to turn it into a decimal, what to do with recurring decimals, and how to do the four operations fast.
Kinds of fractions
All the names for simple and decimal fractions, and which fractions give a terminating decimal.
Simple fractions
The parts of a fraction, proper, improper and mixed fractions, equivalent fractions and reciprocals.
When something is cut into equal parts and we take some of them, we write . The denominator says into how many equal parts the whole was cut; the numerator says how many of them are taken. means: the whole was cut into 8 equal parts and 3 are taken.
| Kind | How to spot it | Example |
|---|---|---|
| Proper fraction | Numerator < denominator (value below 1) | |
| Improper fraction | Numerator ≥ denominator (value 1 or more) | |
| Mixed number | A whole number plus a proper fraction | |
| Like fractions | Same denominators | |
| Unlike fractions | Different denominators | |
| Equivalent fractions | Multiply or divide top and bottom by the same number |
- Mixed → improper: (whole × denominator + numerator).
- Improper → mixed: : 17 ÷ 5 = 3 remainder 2 → .
- Reciprocal: the reciprocal of is ; a fraction × its reciprocal = 1.
- 1First: (4 × 7 + 3) ÷ 7 = 31/7.
- 2Second: 59 ÷ 8 = 7 remainder 3 → .
Decimal fractions: terminating and recurring
What a decimal fraction is, and how to tell in advance whether a fraction gives a terminating or a recurring decimal.
A fraction whose denominator is 10, 100, 1000 … is a decimal fraction, written with a point: . After the point the first place is tenths (1/10), the second hundredths (1/100), the third thousandths (1/1000) …
| Kind | Meaning | Example |
|---|---|---|
| Terminating decimal | Ends after a few digits | |
| Pure recurring | Digits repeat right after the point | , |
| Mixed recurring | A few digits once, then repetition |
- 140 = 2³ × 5 → only 2 and 5 → terminating.
- 212 = 2² × 3 → has a 3 → recurring.
- 3 (dividing 7 by 40).
Changing the form
Turning fractions into decimals, decimals into fractions, and recurring decimals into simple fractions.
Fractions and terminating decimals
Fraction to decimal (by dividing) and terminating decimal to fraction (using a power of 10).
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Recurring decimals to fractions
The rule that gives the fraction straight from the repeating digits.
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The four operations
The four operations on simple fractions and decimals, and the easiest route in each.
Operations on simple fractions
Equalise denominators to add or subtract; multiply numerators and denominators directly; flip the divisor to divide.
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Operations on decimals
Line up the points to add or subtract, count the total decimal places to multiply, make the divisor whole to divide.
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Comparing fractions
Four ways to order fractions and how to pick the fastest.
Four ways to compare
Which method is fastest in each situation.
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Putting in order
Arranging three or four fractions from small to big (or the reverse).
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Word problems
The word “of” means multiply, “the rest” means subtract — one pattern for fraction word problems.
A part of a quantity and the rest
Taking a fraction of a quantity, the reverse question (part to whole) and fractions applied one after another.
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Decimal word problems
Decimal questions about rupees, kilos and metres.
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Choosing the method, traps and fast tricks
Which method for which situation, the commonest slips and some fast tricks.
The commonest mistakes
Mistakes with fractions and decimals are mostly carelessness.
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Fast tricks
A few patterns that shrink a long calculation.
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The practice ladder
New questions of every type, in three levels.
Level 1 — Basic
One-rule questions.
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Level 2 — Standard
Exam-level questions.
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Level 3 — Advanced
Questions at the hard end of competitive exams.
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Revision — formula cards
Read the front, think, then flip.
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