Find the cube root of each of the following natural numbers:
(i) 343
(ii) 2744
(iii) 4913
(iv) 1728
(v) 35937
(vi) 17576
(vii) 134217728
(viii) 48228544
(ix) 74088000
(x) 157464
(xi) 1157625
(xii) 33698267
(i)
Cube root using units digit:
Let us consider 343.
The unit digit is 3; therefore, the unit digit in the cube root of 343 is 7.
There is no number left after striking out the units, tens and hundreds digits of the given number; therefore, the cube root of 343 is 7.
Hence, $\sqrt[3]{343}=7$
(ii)
Cube root using units digit:
Let us consider 2744.
The unit digit is 4; therefore, the unit digit in the cube root of 2744 is 4.
After striking out the units, tens and hundreds digits of the given number, we are left with 2.
Now, 1 is the largest number whose cube is less than or equal to 2.
Therefore, the tens digit of the cube root of 2744 is 1.
Hence, $\sqrt[3]{2744}=14$
(iii)
Cube root using units digit:
Let us consider 4913.
The unit digit is 3; therefore, the unit digit in the cube root of 4913 is 7.
After striking out the units, tens and hundreds digits of the given number, we are left with 4.
Now, 1 is the largest number whose cube is less than or equal to 4.
Therefore, the tens digit of the cube root of 4913 is 1.
Hence, $\sqrt[3]{4913}=17$
(iv)
Cube root using units digit:
Let us consider 1728.
The unit digit is 8; therefore, the unit digit in the cube root of 1728 is 2.
After striking out the units, tens and hundreds digits of the given number, we are left with 1.
Now, 1 is the largest number whose cube is less than or equal to 1.
Therefore, the tens digit of the cube root of 1728 is 1.
Hence, $\sqrt[3]{1728}=12$
(v)
Cube root using units digit:
Let us consider 35937.
The unit digit is 7; therefore, the unit digit in the cube root of 35937 is 3.
After striking out the units, tens and hundreds digits of the given number, we are left with 35.
Now, 3 is the largest number whose cube is less than or equal to $35\left(3^{3}<35<4^{3}\right)$.
Therefore, the tens digit of the cube root of 35937 is 3.
Hence, $\sqrt[3]{35937}=33$
(vi)
Cube root using units digit:
Let us consider the number 17576.
The unit digit is 6; therefore, the unit digit in the cube root of 17576 is 6.
After striking out the units, tens and hundreds digits of the given number, we are left with 17.
Now, 2 is the largest number whose cube is less than or equal to $17\left(2^{3}<17<3^{3}\right)$.
Therefore, the tens digit of the cube root of 17576 is 2.
Hence, $\sqrt[3]{17576}=26$
(vii)
Cube root by factors:
On factorising 134217728 into prime factors, we get:
$134217728=2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 2$ $\times 2 \times 2 \times 2 \times 2 \times 2$
On grouping the factors in triples of equal factors, we get:
$134217728=\{2 \times 2 \times 2\} \times\{2 \times 2 \times 2\} \times\{2 \times 2 \times 2\} \times\{2 \times 2 \times 2\} \times\{2 \times 2 \times 2\} \times\{2 \times 2 \times 2\}$$\times\{2 \times 2 \times 2\} \times\{2 \times 2 \times 2\} \times\{2 \times 2 \times 2\}$
Now, taking one factor from each triple, we get:
$\sqrt[3]{134217728}=2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 2=512$
(viii)
Cube root by factors:
On factorising 48228544 into prime factors, we get:
$48228544=2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 7 \times 7 \times 7 \times 13 \times 13 \times 13$
On grouping the factors in triples of equal factors, we get:
$48228544=\{2 \times 2 \times 2\} \times\{2 \times 2 \times 2\} \times\{7 \times 7 \times 7\} \times\{13 \times 13 \times 13\}$
Now, taking one factor from each triple, we get:
$\sqrt[3]{48228544}=2 \times 2 \times 7 \times 13=364$
(ix)
Cube root by factors:
On factorising 74088000 into prime factors, we get:
$74088000=2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 3 \times 3 \times 3 \times 5 \times 5 \times 5 \times 7 \times 7 \times 7$
On grouping the factors in triples of equal factors, we get:
$74088000=\{2 \times 2 \times 2\} \times\{2 \times 2 \times 2\} \times\{3 \times 3 \times 3\} \times\{5 \times 5 \times 5\} \times\{7 \times 7 \times 7\}$
Now, taking one factor from each triple, we get:
$\sqrt[3]{74088000}=2 \times 2 \times 3 \times 5 \times 7=420$
(x)
Cube root using units digit:
Let is consider 157464.
The unit digit is 4; therefore, the unit digit in the cube root of 157464 is 4.
After striking out the units, tens and hundreds digits of the given number, we are left with 157.
Now, 5 is the largest number whose cube is less than or equal to $157\left(5^{3}<157<6^{3}\right)$
Therefore, the tens digit of the cube root 157464 is 5.
Hence, $\sqrt[3]{157464}=54$
(xi)
Cube root by factors:
On factorising 1157625 into prime factors, we get:
$1157625=3 \times 3 \times 3 \times 5 \times 5 \times 5 \times 7 \times 7 \times 7$
On grouping the factors in triples of equal factors, we get:
Now, taking one factor from each triple, we get:
$\sqrt[3]{1157625}=3 \times 5 \times 7=105$
(xii)
Cube root by factors:
On factorising 33698267 into prime factors, we get
$33698267=17 \times 17 \times 17 \times 19 \times 19 \times 19$
On grouping the factors in triples of equal factors, we get:
$33698267=\{17 \times 17 \times 17\} \times\{19 \times 19 \times 19\}$
Now, taking one factor from each triple, we get:
$\sqrt[3]{33698267}=17 \times 19=323$