1 00:00:00,000 --> 00:00:00,740 2 00:00:00,740 --> 00:00:03,309 Multiply 6 times 1/4. 3 00:00:03,310 --> 00:00:07,160 Simplify your answer and write it as a mixed number. 4 00:00:07,160 --> 00:00:09,169 So let's just do the multiplication. 5 00:00:09,169 --> 00:00:12,469 So at first when you try to multiply 6 times 1/4, you'll 6 00:00:12,470 --> 00:00:14,339 be like, well, gee, I know how to multiply a 7 00:00:14,339 --> 00:00:15,719 fraction times a fraction. 8 00:00:15,720 --> 00:00:18,109 I know how to multiply a whole number times a whole number, 9 00:00:18,109 --> 00:00:20,579 but what about a whole number times a fraction? 10 00:00:20,579 --> 00:00:23,109 And kind of the key insight you need here is that any 11 00:00:23,109 --> 00:00:25,429 whole number can be written as a fraction. 12 00:00:25,429 --> 00:00:31,719 We can rewrite 6 as 6/1, right? 13 00:00:31,719 --> 00:00:34,019 6 divided by 1 is 6. 14 00:00:34,020 --> 00:00:36,220 6 ones is 6. 15 00:00:36,219 --> 00:00:38,359 Depending how you think about it, this is exactly the same 16 00:00:38,359 --> 00:00:39,719 thing as 6. 17 00:00:39,719 --> 00:00:42,210 So we just rewrote our whole number as a fraction. 18 00:00:42,210 --> 00:00:43,320 You can do it for any number. 19 00:00:43,320 --> 00:00:45,609 10 is the same thing as 10/1. 20 00:00:45,609 --> 00:00:54,929 So this become 6/1 times 1/4, and then we just 21 00:00:54,929 --> 00:00:56,159 multiply the fraction. 22 00:00:56,159 --> 00:01:00,739 We multiply the numerators, so this is equal to 6 times 1 as 23 00:01:00,740 --> 00:01:01,590 our numerator. 24 00:01:01,590 --> 00:01:03,519 Let me do that in another color. 25 00:01:03,518 --> 00:01:08,269 So this becomes 6 times 1 for our numerator and 1 times 4 26 00:01:08,269 --> 00:01:11,189 for our denominator, for the number on the bottom. 27 00:01:11,189 --> 00:01:14,259 And so this will become 6 over 4. 28 00:01:14,260 --> 00:01:17,000 And right now, it's just as an improper fraction and it's 29 00:01:17,000 --> 00:01:19,900 also not in lowest terms. You immediately see 6 and 4 are 30 00:01:19,900 --> 00:01:23,190 both divisible by 2, so let's divide them both by 2. 31 00:01:23,189 --> 00:01:25,334 If you divide 6 by 2-- and I'll do it 32 00:01:25,334 --> 00:01:26,370 in a new color again. 33 00:01:26,370 --> 00:01:29,515 If you divide 6 by 2, you get 3. 34 00:01:29,515 --> 00:01:35,290 If you divide 4 by 2, you get 2, so this is equal to 3/2. 35 00:01:35,290 --> 00:01:37,300 So it's still written as an improper fraction. 36 00:01:37,299 --> 00:01:39,569 We now have to write it as a mixed a number. 37 00:01:39,569 --> 00:01:42,349 And the process for writing it as a mixed number, you just 38 00:01:42,349 --> 00:01:45,819 divide the denominator into the numerator, so this just 39 00:01:45,819 --> 00:01:50,919 becomes 2 into 3. 40 00:01:50,920 --> 00:01:53,820 Divide 2 into 3. 41 00:01:53,819 --> 00:01:55,559 2 goes into 3 one time. 42 00:01:55,560 --> 00:01:56,879 1 times 2 is 2. 43 00:01:56,879 --> 00:01:57,929 You subtract. 44 00:01:57,930 --> 00:02:00,680 You have a remainder of 1. 45 00:02:00,680 --> 00:02:10,474 So this will become one whole and 1/2 left over. 46 00:02:10,473 --> 00:02:14,759 47 00:02:14,759 --> 00:02:16,609 So this is 1 and 1/2. 48 00:02:16,610 --> 00:02:17,900 So that's our right answer. 49 00:02:17,900 --> 00:02:20,039 We've just simplified the answer and wrote it is a mixed 50 00:02:20,039 --> 00:02:22,810 number or we could simplify it at this stage. 51 00:02:22,810 --> 00:02:25,830 We could say right here, well, look, we could divide what's 52 00:02:25,830 --> 00:02:29,310 eventually going to be in the numerator by 2 and get a 3 53 00:02:29,310 --> 00:02:31,659 there, and divide what's eventually in the denominator 54 00:02:31,659 --> 00:02:33,990 by 2 and get a 2 there. 55 00:02:33,990 --> 00:02:36,370 3 times 1 is 3. 56 00:02:36,370 --> 00:02:38,985 1 times 2 is 2, so it's 3/2. 57 00:02:38,985 --> 00:02:40,830 And you do this exact same process. 58 00:02:40,830 --> 00:02:44,040 You say that 3/2 is the same thing as 1 and 1/2. 59 00:02:44,039 --> 00:02:47,120 Either one of those will work. 60 00:02:47,120 --> 00:02:48,909 Now let's think about why this makes sense. 61 00:02:48,909 --> 00:02:52,500 Let's think about what 6 times 1/4 is. 62 00:02:52,500 --> 00:02:54,409 Let me draw 1/4. 63 00:02:54,409 --> 00:02:57,129 Let's say that that is 1/4 right there, and 64 00:02:57,129 --> 00:02:58,120 let's do six of them. 65 00:02:58,120 --> 00:03:04,450 So that's 1/4, that's 2/4 that's 3/4, that's 4/4, which 66 00:03:04,449 --> 00:03:08,149 would be a whole, and then you have 5/4, and 67 00:03:08,150 --> 00:03:09,319 then you have 6/4. 68 00:03:09,319 --> 00:03:10,709 So this is 6 times 1/4. 69 00:03:10,710 --> 00:03:13,580 70 00:03:13,580 --> 00:03:15,590 This right here is 4/4. 71 00:03:15,590 --> 00:03:21,090 This right here is 4 over 4, which is equal to a 1, so this 72 00:03:21,090 --> 00:03:22,599 is equal to 1. 73 00:03:22,599 --> 00:03:25,579 And then this right here is two 1/4's, or this 74 00:03:25,580 --> 00:03:28,710 right here is 2/4. 75 00:03:28,710 --> 00:03:31,599 You can imagine this is two out of a potential, if a whole 76 00:03:31,599 --> 00:03:34,299 has to have two more of them, has to have four of them. so 77 00:03:34,300 --> 00:03:42,860 this is 1 and-- let me do it in the same colors-- 1 and 78 00:03:42,860 --> 00:03:45,270 1/2, right? 79 00:03:45,270 --> 00:03:49,719 2 out of 4 is the same thing as 1/2, so this right here is 80 00:03:49,719 --> 00:03:55,930 one out of a possible one, and then two. 81 00:03:55,930 --> 00:04:02,990 So this is 1 and 1/2, which is exactly what we got before. 82 00:04:02,990 --> 00:04:02,998