yego.me
💡 Stop wasting time. Read Youtube instead of watch. Download Chrome Extension

Visually dividing unit fraction by a whole number


2m read
·Nov 11, 2024

We're asked to figure out what is one-seventh divided by four. They help us out with this diagram. We have a whole divided into seven equal sections; each of those is a seventh. We have one of those sevenths filled in, so this is one-seventh right over here. Then, they divide it into four equal sections. In fact, they divide all of the sevenths into four equal sections.

So, one-seventh, which is this whole green bar, divided by four, well that would be this fraction of the whole that is in a question mark. So, can you pause this video and figure out what fraction of the whole is this question mark?

Well, when we divided the first seventh into four equal sections, we also divided all of the sevenths into four equal sections. Now, the entire whole is 28 equal sections because you have a four by seven grid. You have one, two, three, four rows, and you still have your seven columns. You could count them: 7, 14, 21, 28.

So, one-seventh divided by four is going to be one of these 28 sections. So this right over here is 1 over 28. So, this is 1 twenty-eighth.

Let's do another example. We're told to use the number line below to help visualize one-fifth being divided by three. As we go from zero to one on the number line, you could divide into five equal sections, where that's one-fifth, two-fifths, three-fifths, four-fifths, and of course five-fifths is equal to one.

But we want one-fifth divided by three, so we took the section from zero to one-fifth and divided it into three equal sections. The first of those sections, this one right over here, would be one-fifth divided by three.

So, what is this going to be equal to? Pause this video again and see if you can figure that out.

Well, the key realization is that when we divided each of the fifths into three more equal sections, we can now think of each of these steps as a fifteenth because now we have 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 equal sections between 0 and 1.

Where did that 15 come from? Well, we had 5 equal sections and then we split each of those 5 into 3 more equal sections, so 5 times 3 is 15.

So this right over here is 1 fifteenth, this is 2 fifteenths, this is 3 fifteenths, which is equivalent to one-fifth. We could keep going on and on and on, but the key realization here is if I take that first one-fifth and if I divide it into three equal sections and I go only as far as that first of the three equal sections, that is going to be one fifteenth. One fifteenth, and we are done.

More Articles

View All
This school year may be ending but we have lots to do for next year.
Hi, I’m Salon, founder of the Khan Academy, and I just wanted to let you know how excited all of us are for what we have in store this coming back to school. First and foremost, this is going to be a big effort in terms of working with teachers and class…
This Disease is Deadlier Than The Plague
Hello, Steve here. Today I am moving over as the voice of Kurzgesagt for something really special. Our dearest friend John Green would like to tell you a story that’s very close to his heart. So, let’s hear it from him directly. Hey, John! Hey, Steve. T…
Why Do We Clap?
Hey, Vsauce. Michael here. The loudest clap ever recorded clocked in at 113 decibels. And the world record for fastest clapping was recently set at 802 claps per minute. Clapping is the most common human body noise others are meant to hear that doesn’t in…
MARS | Exclusive Sneak Peek
And now an exclusive sneak peek at the first episode of [Music] [Music] Mars Retro Rockets about to fire in 1, 2, 3… bre… 1, 2… [Music] three. We dream it’s who we are, down to our bones, ourselves. That instinct to build, that drive to seek beyond what …
Interpreting y-intercept in regression model | AP Statistics | Khan Academy
Adriana gathered data on different schools’ winning percentages and the average yearly salary of their head coaches in millions of dollars in the years 2000 to 2011. She then created the following scatter plot and trend line. So this is salary in million…
Why the Stock Market Might Not Crash...
So I like to think I make pretty down-to-earth investing videos. I generally try and avoid speculation, I avoid trendy stocks, I avoid hype, and instead, I just focus on rational thinking and rational investment. That has led, you know, to a fair bit of c…