Question : Find the nine rational numbers between 0 and 1.

1. $0.1,0.2,0.3, \ldots, 0.9$
2. $1.1,0.2,10.3, \ldots, 0.9$
3. $0.1,0.2,0.3, \ldots, 20.9$
4. $0.1,0.2,10.3, \ldots, 0.9$

Solution :
Correct option is 1. $0.1,0.2,10.3, \ldots, 0.9$
$0<(0+0.1)=0.1<(0.1+0.1)=0.2<(0.2+0.1)$
$=0.3<\ldots<(0.8+1)=0.9<(0.9+0.1)=1$
$0<0.1<0.2<0.3<\ldots<0.9<1$
$\therefore$ The nine rational numbers between 0 and 1 are $0.1,0.2,0.3, \ldots, 0.9$