1 00:00:00,499 --> 00:00:06,040 Let's see if we can write 0.15 as a fraction. 2 00:00:06,040 --> 00:00:07,900 So the important thing here is to look 3 00:00:07,900 --> 00:00:10,550 at what place these digits are in. 4 00:00:10,550 --> 00:00:13,370 So this 1 right over here, this is in the tenths place, 5 00:00:13,370 --> 00:00:16,550 so you could view that as 1 times 1/10. 6 00:00:16,550 --> 00:00:20,590 This 5 right over here is in the hundredths place, 7 00:00:20,590 --> 00:00:23,700 so you could view that as 5 times 1/100. 8 00:00:23,700 --> 00:00:26,320 So if I were to rewrite this, I can rewrite this 9 00:00:26,320 --> 00:00:30,080 as the sum of-- this 1 represents 1 times 1/10, 10 00:00:30,080 --> 00:00:33,480 so that would literally be 1/10 plus-- 11 00:00:33,480 --> 00:00:36,860 and this 5 represents 5 times 1/100, 12 00:00:36,860 --> 00:00:40,380 so it would be plus 5/100. 13 00:00:40,380 --> 00:00:41,910 And if we want to add them up, we 14 00:00:41,910 --> 00:00:43,870 want to find a common denominator. 15 00:00:43,870 --> 00:00:45,890 The common denominator is 100. 16 00:00:45,890 --> 00:00:49,480 Both 10 and-- the least common multiple. 17 00:00:49,480 --> 00:00:52,720 100 is a multiple of both 10 and 100. 18 00:00:52,720 --> 00:00:55,734 So we can rewrite this as something over 100 19 00:00:55,734 --> 00:00:59,516 plus something over 100. 20 00:00:59,516 --> 00:01:00,640 This isn't going to change. 21 00:01:00,640 --> 00:01:02,750 This was already 5/100. 22 00:01:02,750 --> 00:01:04,650 If we multiply the denominator here 23 00:01:04,650 --> 00:01:07,894 by 10-- that's what we did; we multiplied it by 10-- 24 00:01:07,894 --> 00:01:10,310 then we're going to have to multiply this numerator by 10. 25 00:01:10,310 --> 00:01:12,686 And so this is the same thing as 10/100. 26 00:01:12,686 --> 00:01:13,810 And now we're ready to add. 27 00:01:13,810 --> 00:01:20,660 This is the same thing as-- 10 plus 5 is 15/100. 28 00:01:20,660 --> 00:01:23,010 And you could have done that a little bit quicker just 29 00:01:23,010 --> 00:01:23,860 by inspecting this. 30 00:01:23,860 --> 00:01:26,109 You would say, look, my smallest place right over here 31 00:01:26,109 --> 00:01:27,260 is in the hundredths place. 32 00:01:27,260 --> 00:01:29,590 Instead of calling this 1/10, I could call this 33 00:01:29,590 --> 00:01:30,860 literally 10/100. 34 00:01:30,860 --> 00:01:35,710 Or I could say this whole thing is 15/100. 35 00:01:35,710 --> 00:01:37,914 And now if I want to reduce this to lowest terms, 36 00:01:37,914 --> 00:01:40,330 we can-- let's see, both the numerator and the denominator 37 00:01:40,330 --> 00:01:42,030 are divisible by 5. 38 00:01:42,030 --> 00:01:44,590 So let's divide them both by 5. 39 00:01:44,590 --> 00:01:48,410 And so the numerator, 15 divided by 5, is 3. 40 00:01:48,410 --> 00:01:51,800 The denominator, 100 divided by 5, is 20. 41 00:01:51,800 --> 00:01:55,890 And that's about as simplified as we can get.