Write actual division, find which of the following rational numbers are terminating decimals.
(i) $\frac{13}{80}$
(ii) $\frac{7}{24}$
(iii) $\frac{5}{12}$
(iv) $\frac{31}{375}$
(v) $\frac{16}{125}$
(i) $\frac{13}{80}$
Denominator of $\frac{13}{80}$ is 80 .
And,
$80=2^{4} \times 5$
Therefore, 80 has no other factors than 2 and 5.
Thus, $\frac{13}{80}$ is a terminating decimal.
(ii) $\frac{7}{24}$
Denominator of $\frac{7}{24}$ is 24 .
And,
$24=2^{3} \times 3$
So, 24 has a prime factor 3, which is other than 2 and 5.
Thus, $\frac{7}{24}$ is not a terminating decimal.
(iii) $\frac{5}{12}$
Denominator of $\frac{5}{12}$ is 12 .
$12=2^{2} \times 3$
So, 12 has a prime factor 3, which is other than 2 and 5.
Thus, $\frac{5}{12}$ is not a terminating decimal.
(iv) $\frac{31}{375}$
Denominator of $\frac{31}{375}$ is 375
$375=5^{3} \times 3$
So, the prime factors of 375 are 5 and 3.
Thus, $\frac{31}{375}$ is not a terminating decimal.
(v) $\frac{16}{125}$
Denominator of $\frac{16}{125}$ is 125 .
And,
$125=5^{3}$
Therefore, 125 has no other factors than 2 and $5 .$
Thus, $\frac{16}{125}$ is a terminating decimal