Place value blocks | Math | 4th grade | Khan Academy

What number is shown by the place value blocks?

So here we have several sets of place value blocks, some with many, many, many blocks, and some with just single blocks stacked on top of each other. We want to know what number is represented by all of the blocks combined.

So let's start over here with the single blocks stacked on top of each other because it'll be the easiest one to count. We can zoom in on that a little bit, make it easier for us to count. These are just single blocks, ones stacked on top of each other. So we can count them and we'll see there's one, two, three, four, five, six, seven, eight, nine blocks. Nine blocks right here.

Then moving over, now we have columns of ones and each of these columns... here's nine, because nine is even. Even with this other nine column plus one more is ten. So each of these columns has ten blocks. These are tens. How many tens do we have? We have one, two, three, four, five. Five sets of ten or fifty. So we have 50 blocks here plus 9 more in that last column.

Moving over now, we have these columns of 10, but it's several columns of 10 stuck together to make sort of like a slab. How many columns of 10 are in this slab? There's 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 columns of ten. Ten rows of ten or ten columns of ten, which is a total of one hundred. So each of these slabs is a hundred. And how many slabs do we have? We have one, and then two, a second one back there. So we have two hundreds or two hundred.

Then finally, scooching it over a little bit here, we have these slabs of 100, these sets of 100 all stacked together. So there's one set of 100 here, then another set behind it, and another, and so on. So let's count how many hundreds this is. We have 100, 200, 300, 400, 500, 600, 700, 800, 900, and that last one makes it a thousand. So these are thousands, and how many thousands are there? There are one, two, so two thousand. Two thousands.

Now zooming back out, we can look at all of the amounts we had. We had 2,000 blocks plus 200 more blocks plus 50 more blocks plus nine blocks. Or in total, we have 2,259 blocks.

Moving on to this next one, we know what these different sizes represent here. This first, or this column at the end, is ones. Right beside it, these are columns of 10. We know those are tens. Then we don't have any of the hundreds. Any of the where we had 10 sets of 10 making sort of like a flat slab, we don't have any hundreds in this number. But we do have these large cubes made up of many, many, many small cubes, and those are thousands because they were 10 sets of a hundred.

So now let's count. We have one, two, three, four, five, six, seven, eight ones, which is the same as eight, plus one, two, three tens, which is thirty. Plus no hundreds again, but one, two, three thousands, which is three thousand.

So when we combine these numbers, we need to be careful to remember there are no hundreds. Our number will be three thousand, zero hundreds, and thirty-eight. Three thousand thirty-eight is the number represented by these place value blocks.

For this one, I encourage you to pause the video and see if you can figure out on your own what number is represented by the place value blocks.

And now we can look at it together. Let's remember this is ones, tens, hundreds, and thousands. So looking at our ones, we have one, two, three, four ones. Four ones plus one, two tens, which is twenty. Ten plus ten is twenty, plus... now these hundreds are several hundred. Let's see. 100, 200, 300, 400, 500, 600, 700. There's seven of the hundreds, plus only one of the thousands, which will be one thousand.

And now to combine this, to write this all together, this will be one thousand seven hundred twenty-four is the number shown with these place value blocks.