Hence, 400329 = 0.8225. This is a terminating decimal expansion.
Number Systems - Interactive Study Notes | Bright Tutorials
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Number Systems — Interactive Study Guide
Master the real number system, irrational numbers, surds, rationalisation, and exponent laws.
The Number Hierarchy
Think of numbers as nested boxes: Natural numbers are inside Whole numbers, which are inside Integers, which are inside Rational numbers, which are inside Real numbers.
Key Insight: Between any two rational numbers, there are infinitely many irrational numbers, and vice versa. The number line is “dense” with both types!
Identifying Rational vs Irrational
Number
Type
Reason
√4
Rational
√4 = 2 (perfect square)
√7
Irrational
7 is not a perfect square
0.333...
Rational
Recurring decimal = 1/3
0.10100100010...
Irrational
Non-terminating, non-recurring
π
Irrational
Non-terminating, non-recurring
22/7
Rational
It is p/q form (just an approximation of π)
Rationalisation — Quick Method
To rationalise a denominator with surds, multiply top and bottom by the conjugate:
Conjugate of (a + √b) is (a − √b)
Conjugate of (√a − √b) is (√a + √b)
The denominator becomes rational because (a+b)(a−b) = a² − b².
Quick Self-Check
Is √(16/9) rational or irrational? (Rational: = 4/3)