Q1Written answer
196 is the square of
(a) 11 (b) 12 (c) 14 (d) 16
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Worked solution
Solution:-
(c) 14
Square of 196 is,
= 14 × 14 = 196
NCERT Exemplar · Class 8 · Maths
Chapter 3: Squares and Square Roots & Cubes and Cube Roots
Practice each question, then open the answer or worked solution.
Questions
142 questionsQ2Written answer
Which of the following is a square of an even number?
(a) 144 (b) 169 (c) 441 (d) 625
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Worked solution
Solution:-
(a) 144
Square of even number is 144,
= 12 × 12 = 144
Q3Written answer
A number ending in 9 will have the units place of its square as
(a) 3 (b) 9 (c) 1 (d) 6
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Worked solution
Solution:-
(c) 1
Because, the square of a number having 1 or 9 at the units place ends in 1.
Example: – 11 × 11 = 121
Q4Written answer
Which of the following will have 4 at the units place?
(a) 142 (b) 622 (c) 272 (d) 352
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Worked solution
Solution:-
(b) 622
Because, the square of a number having 2 or 8 at the units place ends in 4.
62 × 62 = 3844
Q5Written answer
How many natural numbers lie between 52 and 62?
(a) 9 (b) 10 (c) 11 (d) 12
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Worked solution
Solution:-
(b) 10
The natural numbers lie between 52 and 62 i.e. 25 and 36 are,
26, 27, 28, 29, 30, 31, 32, 33, 34 and 35
Q6Written answer
Which of the following cannot be a perfect square?
(a) 841 (b) 529 (c) 198 (d) All of the above
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Worked solution
Solution:-
(c) 198
Because, we know that the numbers end with 2, 3, 7 and 8 are not perfect squares.
Q7Written answer
The one’s digit of the cube of 23 is
(a) 6 (b) 7 (c) 3 (d) 9
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Worked solution
Solution:-
(b) 7
The one’s digit of cube 23 i.e. 23 × 23 × 23 = 12,167
So, one’s digit is 7
Q8Written answer
A square board has an area of 144 square units. How long is each side of the board? (a) 11 units (b) 12 units (c) 13 units (d) 14 units
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Worked solution
Solution:-
(b) 12 units
We know that area of square = Side × Side
= 12 × 12
= 144 square units
Q9Written answer
Which letter best represents the location of √25 on a number line?
(a) A (b) B (c) C (d) D
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Worked solution
Solution:-
(c) C
√25 = 5 × 5 = 52 = 25
Q10Written answer
If one member of a Pythagorean triplet is 2m, then the other two members are
(a) m, m2 + 1
(b) m2 + 1, m2 – 1
(c) m2, m2 – 1
(d) m2, m + 1
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Worked solution
Solution:-
(b) m2 + 1, m2 – 1
We know that, for every natural number m > 1, 2m, m2–1 and m2 + 1 form a Pythagorean triplet.