51. Select the perfect square from the following numbers.
(A) 20
(B) 30
(C) 49
(D) 56
Answer:
(C) 49
Explanation:
A perfect square is a number that can be expressed as the product of an integer with itself. Here, 49 is a perfect square because 7 × 7 = 49.
52. A two-digit number whose square ends with digit 6.
(A) 67
(B) 13
(C) 43
(D) 24
Answer:
(D) 24
Explanation:
The square of a number ends in 6 only if the number itself ends in 4 or 6 (since 4×4=16 and 6×6=36). Among the options, 24 ends in 4, and its square is 576.
53. The sum of first 12 consecutive odd number starting with 1 is.
(A)
(B) 106
(C)
(D) 128
Answer:
(A)
Explanation:
The sum of the first ‘n’ consecutive odd numbers is mathematically equal to n^2. Therefore, the sum of the first 12 odd numbers is 12^2.
54. What is the length of the side of a square whose area is 121cm^2.
(A) 21cm
(B) 11cm
(C) 13cm
(D) 09cm
Answer:
(B) 11cm
Explanation:
The area of a square is the side length squared (Area = side^2). To find the side length, take the square root of the area: √121 = 11 cm.
55. The correct expression of (27/343) is.
(A) (3/7)^3
(B) (7/13)^3
(C) (2/6)^3
(D) (4/6)^3
Answer:
(A) (3/7)^3
Explanation:
The number 27 is the cube of 3 (3^3 = 27) and 343 is the cube of 7 (7^3 = 343). Therefore, 27/343 can be correctly expressed as (3/7)^3.
