0:00:00.440,0:00:06.498
Let's see if we can write 0.15 as a fraction.

0:00:06.498,0:00:08.343
So the important thing here is to look at

0:00:08.343,0:00:10.709
what place these digits are in.

0:00:10.709,0:00:13.440
So this 1 right over here, this is in the tenths place.

0:00:13.440,0:00:16.792
So you could view that as 1 × 1/10.

0:00:16.792,0:00:20.830
This 5 right over here is in the hundredths place.

0:00:20.830,0:00:23.800
So you could view that as 5 × 1/100.

0:00:23.800,0:00:25.498
So if I were to rewrite this,

0:00:25.498,0:00:27.551
I can rewrite this as the sum of –

0:00:27.551,0:00:30.003
this 1 represents 1 × 1/10,

0:00:30.003,0:00:33.300
So that would literally be 1/10 – plus –

0:00:33.300,0:00:37.107
And this 5 represents 5 × 1/100.

0:00:37.107,0:00:40.649
So it would be plus 5/100.

0:00:40.649,0:00:41.929
And if we want to add them up,

0:00:41.929,0:00:43.914
if we want to find a common denominator –

0:00:43.914,0:00:46.086
(The common denominator is 100.)

0:00:46.086,0:00:47.841
Both 10 and –

0:00:47.841,0:00:50.561
[100] is the least common multiple.

0:00:50.561,0:00:52.780
[100] is a multiple of both 10 and 100.

0:00:52.780,0:00:59.592
So we can rewrite this as something over 100 plus something over 100.

0:00:59.592,0:01:02.730
This isn't going to change. This was already 5/100.

0:01:02.730,0:01:05.340
If we multiply the denominator here by 10 –

0:01:05.340,0:01:08.180
(That's what we did. We multiplied it by 10.)

0:01:08.180,0:01:10.763
– then we're going to have to multiply this numerator by 10.

0:01:10.763,0:01:12.807
And so this is the same thing as 10/100.

0:01:12.807,0:01:13.880
And now we're ready to add.

0:01:13.880,0:01:20.690
This is the same thing as 10 + 5, is 15/100.

0:01:20.690,0:01:21.982
And you could have done that

0:01:21.982,0:01:23.840
a little bit quicker just by inspecting this.

0:01:23.840,0:01:24.556
You would say, "Look!

0:01:24.556,0:01:27.200
My smallest place right over here is in the hundredths place."

0:01:27.200,0:01:30.760
Instead of calling this 1/10, I could call this literally 10/100.

0:01:30.760,0:01:35.490
Or, I could say this whole thing is 15 100ths.

0:01:35.490,0:01:37.770
And now if I want to reduce this to lowest terms,

0:01:37.770,0:01:39.146
we can – Let's see,

0:01:39.146,0:01:41.810
Both the numerator and the denominator are divisible by 5.

0:01:41.810,0:01:44.898
So let's divide them both by 5.

0:01:44.898,0:01:48.602
And so the numerator, 15, divided by 5 is 3.

0:01:48.602,0:01:51.836
The denominator, 100, divided by 5 is 20.

0:01:51.836,0:01:55.658
And that's about as simplified as we can get.