MEDIUM
CTET Paper 2
IMPORTANT
Earn 100

Find the value of 0.0156253 is:

50% studentsanswered this correctly

Important Points to Remember in Chapter -1 - Square-Square Root and Cube-Cube Root from Arihant Expert Team Mathematics & Pedagogy CTET & TETs Class (VI-VIII) Solutions

Square-Square Root and Cube-Cube Root

Square: If n is a number then it’s square is represented by n raised to the power 2, i.e., n2 and its square root is expressed as n' where √’ is called radical. The value under the root symbol is said to be radicand.

Note:

1. 12 equal to 1

2. Square of positive numbers are always positive in nature.

3. The square of negative numbers is also positive in nature. For example, -32=9

4. Square of zero is zero

5. The square of the root of a number is equal to the value under the root. For example, 32=3

6. The unit place of square of any even number will have an even number only.

7. If a number has 1 or 9 in the unit’s place, then its square ends in 1.

8. If a number has 4 or 6 in the unit’s place, then its square ends in 6.

9. A number having 2, 3, 7 or 8 at unit’s place is never a perfect square. In other words, no square number ends in 2, 3, 7 or 8.

10. For any natural number m greater than 12m,m21,m2+1 is a Pythagorean triplet.

11. Squares of even numbers are always even numbers and square of odd numbers are always odd.

12. The Square of a natural number other than one is either a multiple of 3 or exceeds a multiple of 3 by 1. In other words, a perfect square leaves the remainder 0 or 1 on division by 3.

Procedure to check whether a given natural number is a perfect square or not.

Step I: Obtain the natural number.

Step II: Write the number as a product of prime factors.

Step III: Group the factors in pairs in such a way that both the factors in each pair are equal.

Step IV: See whether some factor is left over or not. If no factor is left over in the grouping, then the given number is a perfect square. Otherwise, it is not a perfect-square.

Step V: To obtain the number whose square is the given number taken over one factor from each group and multiply them.

Square Roots: The square root of a number a is that number which when multiplied by itself gives a as the product. Thus, if b is the square root of a number a, then b×b=a or b2=a. The square root symbol is a.  It follows from this that b=ab2=a

i.e. b is the square root of a if and only if a is the square of b.

Properties of Square Roots

Property 1: If the units digit of a number is 2, 3, 7 or 8, then it does not have root in N (the set of natural numbers).

Property 2: If a number ends in an odd number of zeros, then it does not have a square root. If a square number is followed by an even number of zeros, it has a square root in which the number of zeros in the end is half the number of zeros in the number.

Property 3: The square root of an even square number is even and that root of an odd square number is odd.

Property 4: If a number has a square root in N, then its unit digit must be 0, 1, 4, 5, or 9.

Property 5: Negative numbers have no square root in the system of rational numbers.

9 is not a rational number. It will be a complex number.

Property 6: The sum of first n odd numbers is n2.

Square Root by Prime Factorization Method

Step I: Obtain the given number.

Step II: Resolve the given number into prime factors by successive division.

Step III: Make pairs of prime factors such that both the factors in each pair are equal. Since the number is a perfect square, you will be able to make an exact number of pairs of prime factors.

Step IV: Take one factor from each pair.

Step V: Find the product of factors obtained in step IV.

Step VI: The product obtained in step V is the required square root.

Square Root of Rational Numbers in the Form of Fractions:

Step I: Obtain the fraction

Step II: If the given square root of the numerator and the denominator are the square roots of numerator and denominator respectively of the given fraction.

Step III: Find the square root of the numerator and denominator separately.

Step IV: Obtain the fraction whose numerator and denominator are the square roots of numerator and denominator respectively of the given fraction.

Step V: The fraction obtained in Step IV is the square root of the given fraction.

Cube of Numbers: The number with exponent 3 is called cube.

The word ‘cube’ is used in geometry. A cube is a solid figure which has all its sides equal.

There are only ten perfect cubes from 1 to 1000.

If a number is a number, then the cube of a is a3

a×a×a=a3

Some Properties of Cubes of Natural Numbers are:-

Property 1: Cubes of all even numbers are even.

Property 2: Cubes of all odd natural numbers are odd.

Property 3: The sum of the cubes of first n natural numbers is equal to the square of their sum.

Property 4: Cubes of the numbers ending in digit 1, 4, 5, 6 and 9 are the numbers ending in the same digit.

Cube Root: A number m is the cube root of a number n, if n=m3.

In other words, the cube-root of a number n is that number whose cube gives n.

The cube-root of a number is denoted by n3n3 is also called a radical, n is called the radicand and 3 is called the index of the radical.

Here; 27=33 273=3

Cube Root by Prime Factorization

Step I: Obtain the given number.

Step II: Resolve it into prime factors.

Step III: Group the factors in 3 in such a way that each number of the group is same.

Step IV: Take one factor from each group.

Step V: Find the product of the factors obtained in step IV. This product is the required cube root.

Cube-root of rational-numbers: ab3=a3b3