100+ Square Root and Cube Root Questions for Bank Exams - 1

Question: 1

The least perfect square number divisible by 3, 4, 5, 6 and 8 is

(A) 1200

(B) 2400

(C) 3600

(D) 4800

Ans: C

L.C.M. of 3, 4, 5, 6, 8 is 120. Now, 120 = 2 × 2 × 2 × 3 × 5.

To make it a perfect square, it must be multiplied by 2 × 3 × 5.

So, required number = 22 × 22 × 32 × 52 = 3600.

Question: 2

1.52 × $$√0.0225$$ = ?

(A) 0.3375

(B) 0.0375

(C) 3.275

(D) 32.75

Ans: A

1.52 × $$√0.0225$$ = 1.52 × $$√{225/10000}$$ = $$2.25 × {15}/{100}$$

= 2.25 × 0.15 = 0.3375.

Question: 3

The number of digits in the square root of 625685746009 is

(A) 3

(B) 4

(C) 5

(D) 6

Ans: D

The number of digits in the square root of a perfect square number of n digits is

i. $${n}/{2}$$, if n is even

ii. $${n+1} / {2}$$, if n is odd

iii. Here, n = 12. So required number of digits = $${n}/{2}$$ = $${12}/{2}$$ = 6.

Question: 4

($$√{225/729}$$ - $$√{25/144}$$) ÷ $$√{16/81}$$ = ?

(A) $${1}/{48}$$

(B) $${5}/{16}$$

(C) $${5}/{48}$$

(D) $${6}/{18}$$

Ans: B

Given expression = ($$√225 / √729$$ - $$√25/√144$$) ÷ $$√16 / √81$$

= $$({15}/{27} – {5}/{12})$$ ÷ $${4}/{9}$$ = $$({15}/{108} × {9}/{4})$$ = $${5}/{16}$$.

Question: 5

If $$√3^n$$ = 729, then the value of n is

(A) 6

(B) 8

(C) 10

(D) 12

Ans: D

$$√3^n$$ = 729 = 36 ⇔ ($$√3^n$$)2 = (36)2 ⇔ $$3^n$$ = 312 ⇔ n = 12.

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