1 00:00:00,330 --> 00:00:01,320 - [Instructor] Let's say we wanna figure out 2 00:00:01,320 --> 00:00:04,060 what eight divided by 4/10 is. 3 00:00:04,060 --> 00:00:06,250 Pause this video and try to figure it out on your own 4 00:00:06,250 --> 00:00:08,240 before we do it together. 5 00:00:08,240 --> 00:00:11,150 All right, now one way to approach this is 6 00:00:11,150 --> 00:00:13,280 to think about everything in terms of tenths. 7 00:00:13,280 --> 00:00:15,040 And why tenths, you ask? 8 00:00:15,040 --> 00:00:19,110 Well, I just described the second number as 4/10. 9 00:00:19,110 --> 00:00:21,660 So what would eight be in terms of tenths? 10 00:00:21,660 --> 00:00:24,510 Well, we know that one whole 11 00:00:24,510 --> 00:00:27,163 is equal to 10/10, 12 00:00:28,070 --> 00:00:32,063 so eight wholes is going to be equal to 80/10. 13 00:00:33,370 --> 00:00:34,680 So I could write that down over here. 14 00:00:34,680 --> 00:00:38,400 Instead of eight, I can write that as 80/10. 15 00:00:38,400 --> 00:00:41,580 And I'm taking 80/10 and I'm dividing that by, 16 00:00:41,580 --> 00:00:43,520 divided by 4/10. 17 00:00:43,520 --> 00:00:46,770 I'm just writing out, 4/10. 18 00:00:46,770 --> 00:00:48,860 So if I have 80 of something, 19 00:00:48,860 --> 00:00:52,370 and if I'm diving it into groups of four of that something, 20 00:00:52,370 --> 00:00:54,660 how many equal groups am I going to have? 21 00:00:54,660 --> 00:00:57,430 Well, I'm gonna have 80 divided by four groups, 22 00:00:57,430 --> 00:01:00,390 or 80 divided by four, eight divided by four. 23 00:01:00,390 --> 00:01:01,540 Actually, let me just write that down. 24 00:01:01,540 --> 00:01:05,150 This is going to be equal to 80 over four 25 00:01:05,150 --> 00:01:06,890 or 80 divided by four. 26 00:01:06,890 --> 00:01:08,800 And eight divided by four is two, 27 00:01:08,800 --> 00:01:12,500 so 80 divided by four is going to be equal to 20. 28 00:01:12,500 --> 00:01:16,510 So eight divided by 4/10 is equal to 20. 29 00:01:16,510 --> 00:01:18,630 Another way that you could think about that is 30 00:01:18,630 --> 00:01:20,900 to rewrite eight divided by 4/10 31 00:01:20,900 --> 00:01:25,900 as eight over 4/10. 32 00:01:26,290 --> 00:01:28,320 Over 4/10. 33 00:01:28,320 --> 00:01:30,480 And then if you wanted to rewrite this, 34 00:01:30,480 --> 00:01:32,867 you could say, "Hey, can I multiply the numerator 35 00:01:32,867 --> 00:01:35,727 "and the denominator by some quantity that'll get rid 36 00:01:35,727 --> 00:01:37,840 "of the decimal in the denominator?" 37 00:01:37,840 --> 00:01:40,970 Well, I could multiply the denominator by 10. 38 00:01:40,970 --> 00:01:42,700 And if I don't wanna change the value of the fraction, 39 00:01:42,700 --> 00:01:45,240 I have to multiply the numerator by that same amount. 40 00:01:45,240 --> 00:01:47,180 Well, what does that get us? 41 00:01:47,180 --> 00:01:49,380 Well, this is going to be equal to, 42 00:01:49,380 --> 00:01:51,200 in the denominator right over here, 43 00:01:51,200 --> 00:01:53,180 I'm just going to have a four. 44 00:01:53,180 --> 00:01:55,190 So we got rid of the decimal. 45 00:01:55,190 --> 00:01:58,730 In the numerator, I am going to get 80. 46 00:01:58,730 --> 00:02:02,530 So once again, we get 80 over four, which is equal to 20. 47 00:02:02,530 --> 00:02:03,610 Let's do another example, 48 00:02:03,610 --> 00:02:06,460 but in this case we'll deal with hundredths. 49 00:02:06,460 --> 00:02:09,170 So let's say we want to figure out 50 00:02:09,170 --> 00:02:12,790 what is 48 51 00:02:12,790 --> 00:02:16,710 divided by 0.24 52 00:02:17,870 --> 00:02:20,200 or 24/100? 53 00:02:20,200 --> 00:02:22,400 Pause this video and try to figure that out. 54 00:02:23,410 --> 00:02:26,410 All right, well, we can do something very similar. 55 00:02:26,410 --> 00:02:28,250 This time we're dealing with hundredths, 56 00:02:28,250 --> 00:02:29,940 so we could try to express everything 57 00:02:29,940 --> 00:02:31,630 in terms of hundredths. 58 00:02:31,630 --> 00:02:35,320 So 48 is equal to how many hundredths? 59 00:02:35,320 --> 00:02:39,733 Well, we know that one is equal to 100/100, 60 00:02:42,507 --> 00:02:46,450 so 48 is going to be equal 61 00:02:46,450 --> 00:02:51,450 to 48 times 100/100. 62 00:02:51,670 --> 00:02:53,600 Maybe I'll just write it like that. 63 00:02:53,600 --> 00:02:55,417 Or you might be able to say, "Hey, that's 4,800 64 00:02:55,417 --> 00:02:57,980 "or 4,800/100." 65 00:02:57,980 --> 00:02:59,750 So let's just, actually, I'll write it that way. 66 00:02:59,750 --> 00:03:04,750 This is going to be 4,800/100 67 00:03:07,120 --> 00:03:11,450 divided by, this is 24/100. 68 00:03:11,450 --> 00:03:13,843 24/100. 69 00:03:15,500 --> 00:03:17,360 And so what's that going to be? 70 00:03:17,360 --> 00:03:19,290 Well, same logic as we used up here. 71 00:03:19,290 --> 00:03:22,400 If I have 4,800 of something or 4,800 of something 72 00:03:22,400 --> 00:03:24,540 and if I'm dividing it into equal groups 73 00:03:24,540 --> 00:03:27,100 of 24 of that something, 74 00:03:27,100 --> 00:03:31,430 well, I'm going to have 4,800 divided by 24 equal groups. 75 00:03:31,430 --> 00:03:34,210 So this is going to be equal to 4,800 76 00:03:36,029 --> 00:03:38,160 over 24. 77 00:03:38,160 --> 00:03:42,970 We could express 4,800 as, of course, 48 times a hundred. 78 00:03:42,970 --> 00:03:44,810 So this is equal to 48 79 00:03:44,810 --> 00:03:48,730 times 100 over 24. 80 00:03:48,730 --> 00:03:51,450 And of course, you could view this as the same thing 81 00:03:51,450 --> 00:03:55,103 as this is equal to 48 over 24. 82 00:03:56,070 --> 00:03:59,580 48 over 24, and many of you might have already done it 83 00:03:59,580 --> 00:04:02,193 in your head, times 100. 84 00:04:03,130 --> 00:04:05,820 What's 48 divided by 24? 85 00:04:05,820 --> 00:04:08,290 Well, that is going to be equal to two. 86 00:04:08,290 --> 00:04:11,340 So two times a hundred is equal to 200. 87 00:04:11,340 --> 00:04:14,460 So this right over here is equal to 200. 88 00:04:14,460 --> 00:04:16,300 You can also do it in this type 89 00:04:16,300 --> 00:04:18,630 or do it similar to the way we did this 90 00:04:18,630 --> 00:04:22,710 where instead of expressing it out as words, 91 00:04:22,710 --> 00:04:26,000 you could express it as 48 over 24/100. 92 00:04:26,000 --> 00:04:27,510 And instead of multiplying the numerator 93 00:04:27,510 --> 00:04:28,500 and denominator by 10, 94 00:04:28,500 --> 00:04:30,540 maybe you wanna multiply it by something else 95 00:04:30,540 --> 00:04:33,640 to get whole numbers in both the numerator and denominator. 96 00:04:33,640 --> 00:04:35,030 Think about that after this video, 97 00:04:35,030 --> 00:04:37,053 and try to work it out that way as well.