What is the LCD? 1/9 + 7/30

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What is the LCD? 1/9 + 7/30

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Күн бұрын

How to find the LCD (lowest common denominator).
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Пікірлер: 65

@mikevars8979 Жыл бұрын

I have made it past Dif EQ before I discovered this channel. I am absolutely shock at how bad some of my basic skills are. I never grasped these early skills that would have made my life so much easier. I spent way too much time making sometimes a long list of multiples and then matching them up for a LCD. Sometimes I would just resort to multiplying the denominators and then reducing the fraction. I don't recall ever being taught this tree method in my youth and I started math again at aged 42 in trigonometry. I must say this method is intuitive for me and can just do in my head. I watch this channel all the time just to challenge my brain and pick up some basic skills you wouldn't want to ask your college instructor about in the middle of calc 2.

@peterduffy5388 Жыл бұрын

Seems very complicated to me whereas if you understand your times tables 9 * 10 is 90 and three times 30 is 90 and you have arrived at the LCD since both 9 and 30 are multiples of 90.

@argonwheatbelly637 Жыл бұрын

90. Did it by inspection, but could've used the GCF of 3. Took about 45 seconds. Good problem!

@davidroux7987 Жыл бұрын

Very nice and clear. Even though I often have to do supposedly advanced maths, I'd forgotten how to do this! Thank you

@davidleasure9138 Жыл бұрын

That’s the way I taught it. Thanks for sharing. I like the way you explained taking the biggest power of 3, take the highest power of 3. Awesome

@robertbridgen2950 2 ай бұрын

How I worked this out was 9x30 = 270 now 1/9 + 7/30 I made it 1x30 = 30 and 9x7 = 63 = 93 over 270 Now to make it to the lowest number 93 and 270 I can divide by 3 = 31 /90

@enriqueiii9209 Жыл бұрын

The way I did it, I get 30 no, 60 ,no 90 ,yes. Both 9 and 30 can divide into 90.

@mikevars8979 Жыл бұрын

That is the way I used to do it but if you ever get into higher math that method will cause you a headache. Trust me as that was the only way I knew to do it.

@gadofatumo3290 Жыл бұрын

The final answer is 31/90

@MrMousley 10 ай бұрын

Without working anything out I'm tempted to say 90 1/9 + 7/30 = 10/90 + 21/90 = 31/90 which cannot be simplified but let's just multiply 9 by 30 to get 'a common denominator'' (but not the lowest) 1/9 + 7/30 = 30/270 + 63/470 = 93/270 which can be simplified to 31/90

@quabledistocficklepo3597 Жыл бұрын

I got the answer by increasing 30 until I got the right answer: 30,60, 90. Ninety!! That's it!!! However, I don't understand what you did with the first term. Using your method, it seems to me that the LCD should be calculated as follows: 3x3x. 2x3x5=270. That's the wrong answer, but isn't that the answer you get by using your method?

@pmw3839 11 ай бұрын

Yes, that’s what I thought. I would simply look at the largest denominator (in this case 30), then keep adding 30 until I came to a number that the smaller denominator (in this case 9) goes into without a remainder. But that method would be hard work with bigger and more difficult numbers, or if several fractions with different denominators were being added together. I also agree with what you said about the prime factors. He did, however, say that, if the denominators had the same prime factor, only one should be used, and that one should be the one with the highest power. He didn’t explain why though. I guess it would make the video too long. But I would like to see another video explaining why.

@DeanG55 Жыл бұрын

31/90

@alisonellis7839 Жыл бұрын

@cyruschang1904 4 ай бұрын

9 = 3 x 3 30 = 3 x 10 LCD = 3 x 3 x 10 = 90

@pastorjerrykliner3162 11 ай бұрын

The first question was easy. The second question freaked me out for a second...and then I realized 1408 is just 4*176... Actually figured that out by reducing/simplifying 2/176...it's 1/88...just to get a smaller fraction to work with and then, just for kicks, tried dividing 1408 by 88... Surprise, surprise, surprise... so 1408 IS your LCD.

@mike-yp1uk 10 ай бұрын

I got 90 by prime factoring thanks to tc math

@user-ly6cn3zv5w Жыл бұрын

@myrawalker2657 Жыл бұрын

31 over 90

@mikedickerson1978 Жыл бұрын

I figured out already that the LCM between 9 and 30 is 90. The GCF is 3, and you divide one of the denominators by 3, then multiply by the other denominator, and you get 90. Either 9 times 10 equals 90, or 3 times 30 equals 90. The new equivalent fractions are: for 1/9 plus 7/30, the equivalent fractions are 10/90 plus 21/90, for a sum of 31/90. Also, just for the record, the answer to the other problem you wrote down is 19/1408. With 3/1408 plus 2/176, the LCD between 1408 and 176 is 176 itself. Just take 176 and multiply by 8 and you get 1408. The equivalent fractions are 3/1408 plus 16/1408, and your final answer is 19/1408.

@robertakerman3570 Жыл бұрын

OK!

@TrevorSachko Жыл бұрын

This way seems far to easy for the experts of today. :D

@duggydugg3937 Жыл бұрын

90 ... 31/90

@juanitawatson596 Жыл бұрын

Thank you so much!

@keithterry2169 9 ай бұрын

Find the LCD; exactly the same way that I was taught in school back in 1960.

@Johnmccauley-xm9fp Ай бұрын

@langleywallingford260 Жыл бұрын

31/90 is the answer... The LCD is 90, not 270 (which is 9 * 30).

@rogerdudra178 Жыл бұрын

Greetings from the BIG SKY. A new puzzle.

@user-zk2tz4hj4q Жыл бұрын

Good videos...thanks

@danieldennis9831 Жыл бұрын

LCD is 90 (31/90)

@fredflintstone8048 Жыл бұрын

That one was easy for me even though I didn't do it the best way. I could easily spot that 30 could be multiplied by 3 to come up with 90 which was easy. I then did the rest of the math which gave me 31/90 which I could quickly see as not being able to be simplified which affirmed 90 as being the LCD. Of course I can't do this with larger more complicated denominators within a few seconds as I did with the example problem.

@robertakerman3570 Жыл бұрын

Correct, but He's trying to demonstrate the toolbox at hand for more complicated situations. Foundations are good, I suppose

@fredflintstone8048 Жыл бұрын

@@robertakerman3570 Yes, I know that. I did mention I didn't do it the best way. His way is the best way and covers all scenarios. The example program was easy and I did it all in my head in less than 10 seconds. That won't always be the case.

@robertakerman3570 Жыл бұрын

@@fredflintstone8048 The best part is that U must have had great Instructors. May We count Our blessings.

@fredflintstone8048 Жыл бұрын

@@robertakerman3570 My instructors were fantastic and well beyond me. I should have paid far better attention and studied harder at the time. I've had to go back later in life and relearn many things due to a need I had for using those things in my field of work. I agree, lets count our blessings.

@robertakerman3570 Жыл бұрын

@@fredflintstone8048 Fortunately, when I was in that position; We had calculators(Praise Be).

@mikemassey7403 10 ай бұрын

I get 90, 6×5×3.

@marksolum1794 10 ай бұрын

Who cares about the LCD just find the fastest common denominator, 270, and then reduce if needed. 31/90

@WilliamSmith-yd1vf Жыл бұрын

Yes 90 LCD

@micheleemcdaniel389 Жыл бұрын

How does 3 x 3 end up as 3 squared? Why is there a little '2'? Since it is times 3 why isn't it a little '3'? Why isn't 10 prime?

@pmw3839 11 ай бұрын

Oh dear. You need to go way more basic. 10 is not prime because it can be broken down into smaller factors (2x5). Powers do not mean that the base number is multiplied by the power. They mean that the base number is multiplied by itself the number of times indicated by the power. So, if the base is 3, then 3 squared = 3 multiplied by itself (3x3) And 3 cubed (base 3 with a little 3) = 3x3x3

@mikemassey7403 11 ай бұрын

How about 90!