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Cube Root
Cube Root : The cube root of a given number x is the number whose cube is x. We denote the cube root of x by .
Thus, =
= 3,
=
= 7
■ The cube Root of a negative number is also a negative. ( e.g. = – 2 )
Short Method : For finding a Cube-Root of a perfect cube number.
= 1
= 8
= 27
= 64
= 125
= 216
= 343
= 512
= 729
= 1000
Note : The unit digit of cube-root of a perfect cube number depends on the unit digit of that perfect cube number.
i.e. (i) The unit digit of a cube-root of a perfect cube number remains same when unit digit of that perfect cube number is either 1 or 4 or 5 or 6 or 9 or 0.
(ii) The unit digit of a cube-root of a perfect cube number changed when unit digit of that perfect cube number is either 2 or 3 or 7 or 8. The changes are as follow :
2 8, 3
7
e.g. (i)
( 817
3 and 148 lies between
and
. i.e. 148
5 )
(ii) = 28
( 952
8 and 21 lies between
and
. i.e. 21
2 )
(iii) = 96
( 736
6 and 884 lies between
and
. i.e. 884
9 )
(iiii) = 71
( 911
1 and 357 lies between
and
. i.e. 148
7 )
