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SAI International School
Class VIII

Mathematics
Chapter 7-cubes and cube roots
Lesson note
Subtopic: INTRODUCTION ,PROPERTIES AND PATTERN

SUBTOPICS: CUBE OF A NUMBER, PERFECT CUBE NUMBER, CUBE OF
NEGATIVE INTEGER, CUBE OF RATIONAL NUMBER

1-CUBE OF A NUMBER :

3
If ‘a’ is a non zero number then a x a x a written as a , i.e a raised to power 3 is called
the cube of a or simply ‘a’ cube.‘

2- PERFECT CUBE NUMBER:
A natural number is said to be a perfect cube , if it is
the cube of some natural number.

e.g- 1,8,27,64,125,216,343,512,729 and 1000 etc
are perfect cubes. As

3
1= 1 x 1 x 1= 1
8= 2x2x2=2 3
3
27=3 x3x 3 = 3
64= 4 x 4 x 4= 4 3

3- CUBES OF NEGATIVE INTEGERS:

The cube of a negative integer is always negative.