01) Starting from the extreme right, put a comma for each three digits.
2) Compare the last digit of the number with the following table.
Cube 1=1; cube 2=8 ; cube 3=27 ; cube 4=64 ; cube 5=125 ;
Cube 6 =216 ; cube 7=343 ; cube 8 =512 ; cube 9= 729.
(now its clear that if the given number has last disit 8, the perfect cuberoot will have its last digit 2, if the given number ends with 2, then the perfect cube root will have 8 at its unit digit and so on).
3) Now see the first group of numbers(as the number is divided into groups of three starting from the extreme right) and acertain which numbers cube is less than the LHS that number will become the first digit of the cube root.
Q) 2744
A) 2,744 - given number ends with 4 so as per the table the unit place of the cuberoot would be 4.
now take the LHS where the one number left is 2.the cube which is less than 2 is cube of 1 which is 1 itself, so the answer is 14.
Q) 4913
A) 4,913 - unit place 7, LHS 1, answer = 17
Q) 74088
A) 42
Q) 226981
A) 61
Q) 704969
A) 89 (as cube of 9 is 729 we cant take it, we take the cube of 8 which is 512 which is the cube less than 704).
