Questions · Page 4 of 5

M.C.Q. [1 Marks Each]

MCQ 1511 Mark
What is the one’s digit in the cube root of the cube number $1331$?
  • $1$
  • B
    $2$
  • C
    $3$
  • D
    $4$
Answer
Correct option: A.
$1$
$1 \times 1 \times 1 = 1.$
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MCQ 1521 Mark
If $\text{a}=\frac{1}{\sqrt[3]{\text{b}}}$ ,then $b$ is:
  • A
    $\text{a}^3$
  • B
    $\sqrt{a}$
  • $\frac{1}{\text{a}^3}$
  • D
    $\sqrt[3]{a}$
Answer
Correct option: C.
$\frac{1}{\text{a}^3}$

Given $\text{a}=\frac{1}{\sqrt[3]{\text{b}}}$
$\Rightarrow \text{a}\frac{1}{(\text{b})^\frac{1}{3}}$
Cubing both the sides we get,
$\text{a}^3=\Bigg(\frac{1}{\text{b}^{\frac{1}{3}}}\Bigg)^3=\frac {1}{\text{b}}$
$\Rightarrow\text{b}=\frac{1}{\text{a}^3}$

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MCQ 1531 Mark
Which of the following numbers are perfect cubes?
  • $343$
  • B
    $5324$
  • C
    $108$
  • D
    $243$
Answer
Correct option: A.
$343$
$343$
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MCQ 1541 Mark
Find the smallest number by which the number $121$ must be multiplied to obtain a perfect cube.
  • A
    $7$
  • B
    $9$
  • $11$
  • D
    $15$
Answer
Correct option: C.
$11$
$121 = 11 \times 11.$
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MCQ 1551 Mark
The three numbers are in the ratio $1 : 2 : 3$ the sum of their cubes is $26244.$ What are the numbers?
  • A
    $4, 8, 12$
  • B
    $7, 14, 21$
  • C
    $6, 12, 36$
  • $9, 18, 27$
Answer
Correct option: D.
$9, 18, 27$
Let the numbers be $x, 2 x$ and $3 x$.
According to the given condition,
$(x)^3+(2 x)^3+(3 x)^3=26244 $
$\Rightarrow x^3+8 x^3+27 x^3=26244 $
$\Rightarrow 36 x^3=26244 $
$\Rightarrow x^3=729 $
$\Rightarrow x=\sqrt[3]{729}=9$
Therefore, $2 x=2 \times 9=18$ and $3 x=3 \times 9=27$
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MCQ 1571 Mark
Which of the following numbers is a cube number?
  • $1000$
  • B
    $400$
  • C
    $100$
  • D
    $600$
Answer
Correct option: A.
$1000$
$1000 = 10 \times 10 \times 10 = 10^3$
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MCQ 1581 Mark
The prime factorisation of $64$ is:
  • A
    $2 \times 2 \times 2$
  • B
    $4 \times 4 \times 4$
  • C
    $8 \times 8 \times 8$
  • None of the above.
Answer
Correct option: D.
None of the above.
None of the above.
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MCQ 1591 Mark
What is the one’s digit in the cube root of the cube number $5832$?
  • A
    $2$
  • B
    $4$
  • C
    $6$
  • $8$
Answer
Correct option: D.
$8$
$8 \times 8 \times 8 = 512.$
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MCQ 1601 Mark
The cube of an odd natural number is:
  • A
    Even.
  • Odd.
  • C
    May be even, may be odd.
  • D
    Prime number.
Answer
Correct option: B.
Odd.
$3 \times 3 \times 3 = 27$ (odd).
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MCQ 1611 Mark
Tick $(\checkmark)$ the correct answer: $\Big(1\frac{3}{10}\Big)^3=\ ?$
  • A
    $1\frac{27}{1000}$
  • B
    $2\frac{27}{1000}$
  • $2\frac{197}{1000}$
  • D
    None of these.
Answer
Correct option: C.
$2\frac{197}{1000}$

$\Big(1\frac{3}{10}\Big)^3$
$=\Big(\frac{13}{10}\Big)^3$
$=\frac{13\times13\times13}{10\times10\times10}$
$=\frac{2197}{1000}$
$=2\frac{197}{1000}$

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MCQ 1641 Mark
A natural number is said to be a perfect cube, if it is the cube of some _________.
  • Natural number
  • B
    Square number
  • C
    Cube number
  • D
    Cuboid number
Answer
Correct option: A.
Natural number
Natural number
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MCQ 1651 Mark
Cube of an odd natural number is an _____ number.
  • odd
  • B
    even
  • C
    negative
  • D
    prime
Answer
Correct option: A.
odd
We know, the multiplication of odd natural numbers $3$ times, i.e. the cube of an odd natural number, will always be odd.
That is because an odd number multiplied to another odd number, always yields an odd number.
For example, consider the odd natural numbers $3$ and $5$.
Then, their cube is $33 = 27$ and $53 = 125$, whose units place is odd.
That is, the cubes are also odd.
Hence, the cube of an odd natural number is an odd number.
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MCQ 1661 Mark
The smallest number by which $392$ must be multiplied so that the product is a perfect cube is:
  • A
    $3$
  • B
    $9$
  • C
    $5$
  • $7$
Answer
Correct option: D.
$7$
$7$
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MCQ 1681 Mark
The value of $4\sqrt[3]{1000}$ is:
  • $40$
  • B
    $10$
  • C
    $4$
  • D
    $400$
Answer
Correct option: A.
$40$
$4\sqrt[3]{1000}=4\sqrt[3]{(10\times10\times10)}=4\times10=40$
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MCQ 1691 Mark
Find the smallest number by which the number $200$ must be multiplied to obtain a perfect cube.
  • A
    $2$
  • B
    $100$
  • C
    $10$
  • $5$
Answer
Correct option: D.
$5$
The prime factorisation of $200$ gives
$200 = 2 \times 2 \times 2 v\times 5 \times 5 = 2^3 \times 5 \times 5$
Now multiply by $5$ on both sides.
$200 \times 5 = 2^3 \times 53$
$\big(1000\big)\frac{1}{3}=2\times5=10$
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MCQ 1701 Mark
Find the cube root of the following number by prime factorisation method : $512$
  • A
    $6$
  • $8$
  • C
    $7$
  • D
    $9$
Answer
Correct option: B.
$8$
Prime factorising, we get,
$512 = 2 \times 2 \times 2​ \times 2 \times 2 \times 2 ​\times 2 \times 2 \times 2​$
$= 8 \times 8 \times 8​.$
Here, the factor $8$ occur as triplet. Hence, it is a perfect cube.
Therefore, cube root of $512$, i.e. $\sqrt[3]{512}=8$
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MCQ 1711 Mark
The cube of $23$ is:
  • A
    $2304$
  • B
    $529$
  • C
    $23$
  • $12167$
Answer
Correct option: D.
$12167$
Cube of $23 = 23 \times 23 \times 23 = 12167$
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MCQ 1721 Mark
The smallest natural number by which $243$ must be multiplied to make the product a perfect cube is __________.
  • $3$
  • B
    $9$
  • C
    $8$
  • D
    $7$
Answer
Correct option: A.
$3$
$3$
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MCQ 1731 Mark
Which of the following numbers is a perfect cube?
  • $343$
  • B
    $443$
  • C
    $543$
  • D
    $643$
Answer
Correct option: A.
$343$
$343$
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MCQ 1741 Mark
Which of the following numbers must be subtracted from $345$ to get a perfect cube?
  • A
    $121$
  • B
    $1312$
  • $2$
  • D
    $24$
Answer
Correct option: C.
$2$
$2$
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MCQ 1751 Mark
Mark $(\checkmark)$ against the correct answer: $\frac{\sqrt[3]{128}}{\sqrt[3]{250}}=\ ?$
  • A
    $\frac{3}{5}$
  • $\frac{4}{5}$
  • C
    $\frac{2}{5}$
  • D
    None of these.
Answer
Correct option: B.
$\frac{4}{5}$

Resolving the numerator and the denominator into prime factors:
$\frac{\sqrt[3]{128}}{\sqrt[3]{250}}$
$=\sqrt[3]{\frac{128}{250}}$
$=\sqrt[3]{\frac{2\times8\times8}{2\times5\times5\times5}}$
$=\sqrt[3]{\frac{\not{2}\times8\times8}{\not{2}\times5\times5\times5}}$
$=\sqrt[3]{\frac{8\times8}{5\times5\times5}}$
$=\sqrt[3]{\frac{(2)^3\times(2)^3}{(5)^3}}$
$=\frac{2\times2}{5}$
$=\frac{4}{5}$

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MCQ 1771 Mark
Tick $(\checkmark)$ the correct answer: Which of the following numbers is a perfect cube?
  • A
    $1152$
  • $1331$
  • C
    $2016$
  • D
    $739$
Answer
Correct option: B.
$1331$
$A.$  $1152$
$= 2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 3 \times 3$
$= 2^3 \times 2^3 \times 3^2$
$\begin{array}{c|c}2&1152\\\hline2&576\\\hline2&288\\\hline2&144\\\hline2&72\\\hline2&36\\\hline2&18\\\hline3&9\\\hline3&3\\\hline&1\end{array}$
$B.$  $1131$
$= 11 \times 11 \times 11$
$= (11)^3$
$\begin{array}{c|c}11&1331\\\hline11&121\\\hline11&11\\\hline&1\end{array}$
$C.$  $2016$
$​​​​​​​​​​​​​​= 2 \times 2 \times 2 \times 2 \times 2 \times 3 \times 3 \times 7$
$= 2^3 \times 2 \times 2 \times 3 \times 3 \times 7$
$\begin{array}{c|c}2&2016\\\hline2&1008\\\hline2&504\\\hline2&252\\\hline2&126\\\hline3&63\\\hline3&21\\\hline7&7\\\hline&1\end{array}$
$D.$  $739$
$= 1 \times 739$
We see that $1331$ is a perfect cube.
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MCQ 1781 Mark
What should be divided by $53240$ to make it a perfect cube?
  • A
    $10$
  • B
    $20$
  • $5$
  • D
    $15$
Answer
Correct option: C.
$5$
The prime factorisation of $53240$
$53240 = 2 \times 2 \times 2 \times 11 \times 11 \times 11 \times 5 = 2^3 \times 11^3 \times 5$
Hence, we need to divide $53240$ by $5$
$\frac{53240}{5}=10648$ is a perfect cube.
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MCQ 1791 Mark
Which among the following is a perfect cube?
  • A
    $400$
  • $15625$
  • C
    $243$
  • D
    $9000$
Answer
Correct option: B.
$15625$
$400 = 2 \times 2 \times 2 \times 2 \times 5 \times 5; 2 \times 5 \times 5$ remains after grouping into triplets.Therefore, it is not a perfect square.
$15625 = 5 \times 5 \times 5 \times 5 \times 5 \times 5$ In this factorization, nothing remains after grouping $S'$s in triplets. Therefore, it is a perfect square.
$243 = 3 \times 3 \times 3 \times 3 \times 3$ In this factorization $3 \times 3$ remains after grouping $3'$ in triplets. Hence, it is not a perfect square.
$9000 = 3 \times 3 \times 2 \times 2 \times 2 \times 5 \times 5 \times 5$ In this factorization $3 \times 3$ remains after groping $5's$ and $2's$ in triplets.
Hence, it is not a perfect. Square.
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MCQ 1801 Mark
The one’s digit of the cube of the number $347$ is:
  • $3$
  • B
    $4$
  • C
    $7$
  • D
    $1$
Answer
Correct option: A.
$3$
$7 \times 7 \times 7 = 343.$
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MCQ 1811 Mark
Which among is the smallest number by which we should multiply $6125$ to get a perfect cube?
  • A
    $3$
  • B
    $2$
  • $7$
  • D
    $5$
Answer
Correct option: C.
$7$
The prime factorization of $6125$ is:$ 5 \times 5 \times 5 \times 7 \times 7$
Here the prime factor $7$ does not appear in a group of three. To make it a perfect number, we need one more $7$
In that case $6125 \times 7 = 5 \times 5 \times 5 \times 7 \times 7 = 42875$ which is a perfect cube.
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MCQ 1851 Mark
How many zeros will be there in the cube root of $800$?
  • A
    $3$
  • B
    $0$
  • C
    $1$
  • cube root does not exist
Answer
Correct option: D.
cube root does not exist
cube root does not exist
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MCQ 1861 Mark
 How many zeros will be there in the cube root of $27000$?
  • A
    $3$
  • B
    $0$
  • $1$
  • D
    $2$
Answer
Correct option: C.
$1$
$1$
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MCQ 1881 Mark
 How many digits will be there in the cube root of $512$?
  • $1$
  • B
    $2$
  • C
    $3$
  • D
    $4$
Answer
Correct option: A.
$1$
$1$
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MCQ 1891 Mark
 How many digits will be there in the cube root of $46656$?
  • $2$
  • B
    $1$
  • C
    $3$
  • D
    $4$
Answer
Correct option: A.
$2$
$2$
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MCQ 1901 Mark
The number of digits in the cube root of a $6$-digit number is _______ .
  • A
    $3$
  • $2$
  • C
    $4$
  • D
    $6$
Answer
Correct option: B.
$2$
$2$
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MCQ 1921 Mark
 What will be the unit digit of the cube root of a number ends with 7?
  • $3$
  • B
    $7$
  • C
    $6$
  • D
    $5$
Answer
Correct option: A.
$3$
$3$
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MCQ 1931 Mark
 What will be the unit digit of the cube root of a number ends with $3$?
  • A
    $3$
  • $7$
  • C
    $5$
  • D
    $2$
Answer
Correct option: B.
$7$
$7$
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MCQ 1941 Mark
What will be the unit digit of the cube root of a number ends with $2$?
  • A
    $2$
  • $8$
  • C
    $4$
  • D
    $6$
Answer
Correct option: B.
$8$
$8$
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MCQ 1951 Mark
 What will be the unit digit of the cube root of a number ends with $8$?
  • $2$
  • B
    $8$
  • C
    $4$
  • D
    $6$
Answer
Correct option: A.
$2$
$2$
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MCQ 1961 Mark
 If the volume of a cube is $125\ cm^3$ then what would be the length of its side?
  • A
    $25$
  • $5$
  • C
    $4$
  • D
    $15$
Answer
Correct option: B.
$5$
$5$
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MCQ 1971 Mark
Which of the following is true for any natural number $n$?
  • A
    $n^{2}>n^{3}$
  • $n^{3}>n^{2}$
  • C
    $n^{2}=n^{3}$
  • D
    none of these
Answer
Correct option: B.
$n^{3}>n^{2}$
$n^{3}>n^{2}$
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MCQ 2001 Mark
The symbol for cube root is
  • A
    $\sqrt{3}$
  • $\sqrt[3]{\square}$
  • C
    $\sqrt{3}$
  • D
    $\sqrt[2]{3}$
Answer
Correct option: B.
$\sqrt[3]{\square}$
$\sqrt[3]{\square}$
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