(i) Pure Recurring Decimal :
A decimal fraction in which all the figures (or digits) occur repeatedly, is called a pure recurring decimal .
e.g . 9.3333, 0.454545, 0.1111

(ii)Mixed Recurring Decimal:
A decimal fraction in which some of the digits do not occur repeatedly is called is called a mixed recurring decimal.
e.g. 3.2444, 0.4636363, 27.93222.

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Convert Pure Recurring Decimal into p/q form
Put as many 9's in the denominator as the number of digits in the period of decimal number, in numerator put number as it is or subtract digit (before decimal) from the number.
e.g.
(i) 0.999 = 9/9 = 1
(ii) 0.727272 = 72/99
(iii) 5.717171 = 566/99.

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Convert Mixed Recurring Decimal into p/q form
In numerator, put the number and then subtract it from the formed by the non - recurring digits.

In denominator, put as many 9's as there are digits in the period of the recurring decimal followed by as many zeros as there is number of digits which are not recurring after the decimal point.
e.g.
(i) 0.2454545 = 243/990
(ii) 0.8727272 = 864/990
(iii) 9.072222 = 8165/900