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Published on: 21/10/2025
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Questions + Answers key
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1.
The perimeters of two squares are 40 m and 96 m, respectively. Find the perimeter of another square, equal in area to the sum of the first two squares.
2.
Find the value of \(\frac { \sqrt { 25.4016 } -\sqrt { 1.0609 } }{ \sqrt { 25.4016 } +\sqrt { 1.0609 } } \)
3.
If a number contains 3 zeros at the end, how many zeros will its square have? What do you notice about the number of zeros at the end of the number and the number of zeros at the end of its square? Can we say square numbers can only have even number of zeros at the end ?
4.
What will be the unit digit of the squares of the following numbers?
12796
5.
Find the value of \(\sqrt { 16+\sqrt { 81 } } \)
6.
If \(\sqrt { x } +43=\sqrt { 19881 } \) , then find the value of x.
7.
Find the number of digits in the square root of each of the following numbers (without any calculation). 390625
8.
Without calculating square root, find the number of digits in the square root of the following numbers. 36864
9.
What could be the possible one's digits of the square root of each of the following numbers? 657666025
10.
If 112 = 121,what is the square root of 121?
11.
Write a Pythagorean triplet whose one member is 18
12.
Write a Pythagorean triplet whose one member is 16
13.
Find the squares of the following numbers containing 5 in unit's place. 15
14.
The following numbers are obviously not perfect squares. Give reason.222000
15.
What will be the unit's digit of the squares of the following numbers? 272
16.
How many non square numbers lie between the following pairs of numbers? 1002 and 1012
17.
What will be the one's digit in the square of the following numbers? 21222
18.
Which of the following numbers would have digit 6 at unit's place? 262
19.
Which of 1232,772,822,1612,1092 would end with digit 1?
20.
Find the perfect square numbers between 50 and 60
21.
If a number of n-digits is a perfect square and' n' is an even, then which of the following is the number of digits of its square root?
\(\frac{n-1}{2}\)
\(\frac{n}{2}\)
\(\frac{n+1}{2}\)
2n
22.
Which of the following is the number of non-perfect square numbers between the squares of the numbers nand n + 1?
n + 1
n
2n
2n+1
23.
Which letter best represents the location of \(\sqrt { 25 } \) on a number line?

A
B
C
D
24.
169 is the square of
11
12
13
14
1.
Let side of two squares be a1 and a2·
Then, perimeter of first square = 4a1
According to the question,
Perimeter = 40
\(\therefore\) 4a1 = 40 \(\Rightarrow\) a1 = 10
Similarly, second square's perimeter = 4a2
But according to the question,
Perimeter = 96
\(\therefore\) 4a2 = 96 \(\Rightarrow\) a2 = 24
Let a be the side of another square.
Now, sum of the areas of first and second square area of
= Area of (first square) + (Area of second square)
=\({ a }_{ 1 }^{ 2 }+{ a }_{ 2 }^{ 2 }\)
Area =(10)2 + (24)2 =100 + 576
\(\therefore\) Area = 676
\(\Rightarrow\)a2 = 676 \(\Rightarrow\) a = \(\sqrt { 676 } \)
Then, a=26 m
Another square's perimeter = 4a = 4 x 26 = 104 m
So, perimeter of another square is 104 m.
2.
\(\frac { 401 }{ 607 } \)
3.
If a number contains 3 zeros at the end, then its square will have 3\(\times\)2 = 6 zeros at the end
The number of zeros at the end of a number
=\(\frac { 1 }{ 2 } \times \) The number of zeros at the end of its square
Yes ; we can say that square numbers can only have even number of zeros at the end.
4.
Since 6 x 6 = 36
\(\therefore\) The unit digit of (12796) will be 6.
5.
We have, \(\sqrt { 16+\sqrt { 81 } } =\sqrt { 16+9 } =\sqrt { 25 } =5\)
6.
9604
7.
Given number is 390625.
Here, number of digits, n = 6 [even]
\(\therefore\) Number of digits in the square root of 390625
\(=\frac { n }{ 2 } =\frac { 6 }{ 2 } =3\)
Hence, the number of digits in the square root of 390625 is 3 digits.
8.
Given number is 36864.
Here, number of digits, n = 5 [odd]
\(\therefore\) Number of digits in the square root of 36864
\(\frac { n+1 }{ 2 } =\frac { 5+1 }{ 2 } =\frac { 6 }{ 2 } =3\)
Hence, the number of digits in the square root of 36864 is 3 digits.
9.
The possible one's digits of the square root of the numbers.
In a given number 657666025, one's digit is 5.
We know that, square of5 gives out 5 in one's digit.
Hence, possible one's digit of the square root digit is 5.
10.
We have, 112 = 121
Therefore, the square root of 121 is 11.
11.
Let 2m = 18
⇒ m =\(\frac { 18 }{ 2 } \) =9
∴ m2 - 1 = 92 - 1 = 81 - 1 = 80
and m2 +1 = 92 +1 = 81 + 1 = 80
So, a Pythagorean triplet, whose one number is 18, is 18, 80, 82.
12.
Let 2m = 16
⇒ m =\(\frac { 16 }{ 2 } \) = 8
∴ m2- 1 = 82 - 1 = 64 - 1 = 63
and m2+ 1 = 82 + 1 = 64 +1 = 65
So, a Pythagorean triplet, whose one number is 16, is 16, 63, 65
13.
152 = 1\(\times\)(1+1)\(\times\)hundreds + 25
=(1\(\times\)2)\(\times\)100 + 25 = 200 + 25 = 225
14.
The given number 222000 ends with 0, so it cannot be a perfect square due to odd number of zeroes.
15.
Given number is 272.
Unit's digit of 272 = 2
So, the square of unit's digit = 22 = 4
Hence, unit's digit of the square of unit's digit of the given number is 4.
16.
Given, pair of numbers 1002 and 1012.
Non-square numbers between 1002 and 1012 = 2n
= 2 \(\times\) 100 = 200 [\(\because\)n=100]
17.
Given number is 21222.
Unit's digit of 21222 = 2
So, square of unit's digit = (2)2 = 4
Hence, unit's digit of the square of unit's digit of the given number is 4.
18.
Since, number 26 ends with digit 6, so the number getting from the square of 26, will be the end of the digit 6.
19.
We know that, if a number has 1 or 9 in the unit's place, then its square ends with digit 1. Therefore,1612 and 1092 would end with digit 1.
20.
We know that,
7 X 7 = 49 and 8 X 8 = 64
Hence, there is no perfect square number lying between 50 and 60.
21.
(b)
\(\frac{n}{2}\)
22.
(c)
2n
23.
(c)
C
24.
(c)
13
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