What is the least number by which 19,600 must be divided to make the quotient a perfect square?
19,600 = 2⁴ × 5² × 7²
Every prime already has an even power
19,600 = 140² is itself a perfect square → divide by 1
Answer: 1
Square Roots & Cube Roots · Exercise 4 of 6
65 mixed-level square root and cube root questions in the style of IBPS/SBI ("√? = …"), SSC CGL/CHSL, RRB NTPC and Group D, UPSC CSAT, state exams and campus placements. Use them as a timed speed drill.
What is the least number by which 19,600 must be divided to make the quotient a perfect square?
19,600 = 2⁴ × 5² × 7²
Every prime already has an even power
19,600 = 140² is itself a perfect square → divide by 1
Answer: 1
If √(x + 9) = 7, find x.
Square both sides: x + 9 = 49
x = 40
Answer: 40
If ∛(x/8) = 1.5, find x.
Cube both sides: x/8 = 1.5³ = 3.375
x = 3.375 × 8 = 27
Answer: 27
What is (√3 + √2)(√3 − √2)?
Formula: (a + b)(a − b) = a² − b²
= 3 − 2 = 1
Answer: 1
Evaluate √0.0064.
√64 = 8
4 decimal places → 2 in the root
√0.0064 = 0.08
Answer: 0.08
√14641 = ?
Unit digit 1 → root ends in 1 or 9
Drop the last two digits: 146 → 12² = 144 ≤ 146 → tens part 12
Compare with 125² = 15,625: 14,641 is smaller → 121
Answer: 121
Which two consecutive natural numbers have squares that differ by 31?
(n + 1)² − n² = 2n + 1 = 31
n = 15
The numbers are 15 and 16
Answer: 15 and 16
The sum of a number and its square root is 72. What is the number?
Let √x = t: t² + t = 72
t² + t − 72 = 0 → (t + 9)(t − 8) = 0
t = 8 → x = 64
Answer: 64
∛(3 3/8) = ?
3 3/8 = 27/8
∛27 = 3 and ∛8 = 2
Answer: 3/2
What is the square of 0.07?
7² = 49
0.07 has 2 decimal places → the square has 4
0.07² = 0.0049
Answer: 0.0049
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