PSEB 8th Class Maths Solutions Chapter 6 Squares and Square Roots Ex 6.1

Punjab State Board PSEB 8th Class Maths Book Solutions Chapter 6 Squares and Square Roots Ex 6.1 Textbook Exercise Questions and Answers.

PSEB Solutions for Class 8 Maths Chapter 6 Squares and Square Roots Ex 6.1

1. What will be the unit digit of the squares of the following numbers?

Question (i).
81
Solution:
81
Here, the ending digit is 1.
1 × 1 = 1
∴ The unit digit of (81)² will be 1.

Question (ii).
272
Solution:
272
Here, the ending digit is 2.
2 × 2 = 4
∴ The unit digit of (272)² will be 4.

Question (iii).
799
Solution:
799
Here, the ending digit is 9.
9 × 9 = 81
∴ The unit digit of (799)² will be 1.

Question (iv).
3853
Solution:
3853
Here, the ending digit is 3.
3 × 3 = 9
∴ The unit digit of (3853)² will be 9.

Question (v).
1234
Solution:
1234
Here, the ending digit is 4.
4 × 4 = 16
∴ The unit digit of (1234)² will be 6.

Question (vi).
26387
Solution:
26387
Here, the ending digit is 7.
7 × 7 = 49
∴ The unit digit of (26387)² will be 9.

Question (vii).
52698
Solution:
52698
Here, the ending digit is 8.
8 × 8 = 64
∴ The unit digit of (52698)² will be 4.

Question (viii).
99880
Solution:
99880
Here, the ending digit is 0.
0 × 0 = 0
∴ The unit digit of (99880)² will be 0.

Question (ix).
12796
Solution:
12796
Here, the ending digit is 6.
6 × 6 = 36
∴ The unit digit of (12796)² will be 6.

Question (x).
55555
Solution:
55555
Here, the ending digit is 5.
5 × 5 = 25
∴ The unit digit of (55555)² will be 5.

2. The following numbers are obviously not perfect squares. Give reason:

Question (i).
1057
Solution:
1057
Here, the ending digit is 7, which is not one of the digits 0, 1, 4, 5, 6 or 9.
∴ 1057 is not a perfect square.

Question (ii).
23453
Solution:
23453
Here, the ending digit is 3, which is not one of the digits 0, 1, 4, 5, 6 or 9.
∴ 23453 is not a perfect square.

Question (iii).
7928
Solution:
7928
Here, the ending digit is 8, which is not one of the digits 0, 1, 4, 5, 6 or 9.
∴ 7928 is not a perfect square.

Question (iv).
222222
Solution:
222222
Here, the ending digit is 2, which is not one of the digits 0, 1, 4, 5, 6 or 9.
∴ 222222 is not a perfect square.

Question (v).
64000
Solution:
64000
Here, the number of zeros at the end is odd.
∴ 64000 is not a perfect square.

Question (vi).
89722
Solution:
89722
Here, the ending digit is 2, which is not one of the digits 0, 1, 4, 5, 6 or 9.
∴ 89722 is not a perfect square.

Question (vii).
222000
Solution:
222000
Here, the number of zeros at the end is odd.
∴ 222000 is not a perfect square.

Question (viii).
505050
Solution:
505050
Here, the ending digit is 0. (Number of odd zero.)
∴ 505050 is not a perfect square.

3. The squares of which of the following would be odd numbers ?

(i) 431
(ii) 2826
(iii) 7779
(iv) 82004
Solution:
[Note: The square of an odd natural number is odd and that of an even number is an even number.]
(i) 431
This is an odd number.
∴ (431)² is an odd number.

(iii) 7779
This is an odd number.
∴ (7779)² is an odd number.

4. Observe the following pattern and find the missing digits:

Solution :
Observing the above pattern, we can find the missing digits as follows :

5. Observe the following pattern and supply the missing numbers :

Solution:
Observing the above pattern, we can find the missing numbers as follows :

6. Using the given pattern, find the missing numbers:
1² + 2² + 2² = 3²
2² + 3² + 6² = 7²
3² + 4² + 12² = 13²
4² + 5² + …….² = 21²
5² + ……² + 30² = 31²
6² + 7² + ……² = ……²
[To find pattern:
Third number is related to first and second number. How?
Fourth number is related to third number. How?]
Solution:
(a)² + (a + 1)² + {a (a + 1 )}²
= {a (a + 1) + 1}²
The missing numbers are :
1² + 2² + 2² = 3²
2² + 3² + 6² = 7²
3² + 4² + 12² = 13²
4² + 5² + 20² = 21²
5² + 6² + 30² = 31²
6² + 7² + 42² = 43²

7. Without adding, find the sum:

Question (i).
1 + 3 + 5 + 7 + 9
Solution:
The sum of first five odd numbers = 5²
= 5 × 5
= 25

Question (ii).
1 + 3 + 5 + 7 + 9 + 11 + 13 + 15 + 17 + 19
Solution:
The sum of first ten odd numbers = 10²
= 10 × 10
= 100

Question (iii).
1 + 3 + 5 + 7 + 9 + 11 + 13 + 15 + 17 + 19 + 21 + 23
Solution:
The sum of first twelve odd numbers = 12²
= 12 × 12
= 144

8.

Question (i).
Express 49 as the sum of 7 odd numbers.
Solution:
49 = 7² = Sum of first seven odd numbers
∴ 49 = 1 + 3 + 5 + 7 + 9 + 11 + 13

Question (ii).
Express 121 as the sum of 11 odd numbers.
Solution :
121 = 11² = Sum of first eleven odd numbers
∴ 121 = 1 + 3 + 5 + 7 + 9 + 11 + 13 + 15 + 17 + 19 + 21

9. How many numbers lie between squares of the following numbers?
[Note : Between n² and (n + 1)², there are 2n non-square numbers.]

Question (i).
12 and 13
Solution:
Natural numbers between 12² and 13²
= 2 × 12
= 24. (2n, n = 12)

Question (ii).
25 and 26
Solution:
Natural numbers between 25² and 26²
= 2 × 25
= 50. (2n, n = 25)

Question (iii).
99 and 100
Solution:
Natural numbers between 99² and 100²
= 2 × 99
= 198. (2n, n = 99)