0.25=25/100=¼. So between 0 and 1 there are 4 subdivisions because 4×¼=1 or 4=1÷¼.
So the first pair is 0 and ¼, which is the same as 0 and 0.25;
the next pair is ¼ and ¼+¼=2/4=½, so that’s ¼ and ½, or 0.25 and 0.25+0.25=0.50;
the next pair is ½ and ½+¼=¾, so that’s ½ and ¾, or 0.50 and 0.50+0.25=0.75;
the last pair is ¾ and ¾+¼=4/4=1, which is ¾ and 1, or 0.75 and 1.
That gives us the pairs 0 and 0.25, 0.25 and 0.50, 0.50 and 0.75, 0.75 and 1.