Answer:
9/20 yes, 4/15 not. See below
Step-by-step explanation:
Pick 9/20 and multiply numerator and denominator by 5:
9/20 = 45/100
We know that if we divide a number by 100 we need to move the coma as two places left, so:
9/20 = 45/100 = 0.45
And this is a terminal decimal as we know where it ends.
On the other hand if we pick 4/15 let try to divide it (here I will do it 'manually'):
4 |_ 15
we can divide 4 by 15, so we use 40 and begin with a comma
40 |_ 15
0.
15 enters 2 times in 40 with a rest of 10, so:
40 |_ 15
30 0.2
100
100 divided by 15 is 6 and we have 10 as rest again, and again and again...
40 |_ 15
30 0.266.....
100
100
....
So, we will have 0.266666666666666 infinitely. The decimal for 4/15 is non terminating and is 0.26666666666666666...
