Rounding Off To Nearest Tens, Hundreds And Thousands
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00:00Hi kids! Today we will learn rounding off the numbers. First of all, what is rounding
00:08off? Rounding is to replace the number with another one that has value approximately equal
00:18to our original number, but is simpler, shorter, and easier to represent and use in any calculation.
00:28It makes no less exact, but simpler to calculate. Rounding can be to the nearest 10, nearest 100,
00:39or nearest 1000. Rounding off to nearest 10. So let's first learn rounding to the nearest 10.
00:49Here are a few numbers, 12, 34, 27, 88, 45, 65. We have to round them up to the nearest 10. Let's
01:04start with 12. See the number line? Where can you fit 12 on this number line? It is somewhere
01:15between 10 and 20. Whenever you want to round a number, there are always two options. Either
01:25we can round it down to 10, or round it up to 20. Think, which option do you think is more apt?
01:35Here is a rule to help you. We have a 5 mark midway between the two 10s, always. If the number
01:47is above the 5 mark, you round it up. And if the number is below 5 mark, you round it down. Here,
01:5912 is below the 5 mark. Also, 12 is only two numbers away from 10, whereas it is
02:08eight numbers away from 20. So we will round it down to 10. Okay, let's take the next number,
02:2065. Where can you fit 65 on this number line? It is somewhere between 60 and 70. Whenever you
02:34want to round a number, there are always two options. Either we can round it down to 60,
02:42or round it up to 70. Think, which option do you think is more apt? Here, 65 is midway between 60
02:56and 70, or it is on the 5 mark. What do we do now? 65 is five numbers away from 60.
03:10And five numbers away from 70. Here we have a simple rule. Whenever a number is on the 5 mark,
03:20we always round it up. See the figure. The numbers 0 to 4 are rounded down to 0. And 5 to 9
03:33are rounded up to 10. Likewise, 11 to 14 are rounded down to 10. And 15 to 19 are rounded up
03:46to 20. Numbers 21 to 24 are rounded down to 20. Numbers 25 to 29 are rounded up to 30.
04:00So kids, we learned that in rounding off to nearest 10, numbers are rounded down if it's
04:08below the 5 mark, and rounded up if it's on or above the 5 mark. Now let's learn what is rounding
04:17off to the nearest 100. Here we have a few numbers. 12, 68, 123, 167, 199. We have to round
04:35them up to the nearest 100, 12. Let's start with 12. See the number line. Where can you fit 12
04:48on this number line? It is somewhere between 0 and 100. Whenever you want to round a number,
04:59there are always two options. Either we can round it down to previous 100 or round it up to next
05:09100. Think, which option do you think is more apt? Here is a rule to help you. You have a 50 mark
05:21midway between 200, as there was a 5 mark when you round off numbers to nearest 10.
05:31If the number is above the 50 mark, you round it up. And if the number is below 50 mark,
05:38you round it down. Here, 12 is below the 50 mark, so we will round it down to 0.
05:48Okay, let's take the next number, 68. We have to round 68 to nearest 100. Let's see where we can
06:00fit 68 on this number line. It is somewhere between 0 and 100. So we have two options.
06:12Either round it down or we can round it up, that is to 100, that is to 0. Think, according to the
06:24rule, if the number comes after the 50 mark, the number is rounded up. And if the number comes
06:33before the 50 mark, the number is rounded down. So here our number 68 is after the 50 mark,
06:44so we will round it up to 100. Now let's take another example, 123.
06:54We have to round 123 to the nearest 100. Let's see where we can fit 123 on this number line.
07:09It is somewhere between 100 and 200. Here our number 123 is before the 50 mark,
07:21so we will round it down to 100. Now let's take another example,
07:30278. We have to round 278 to the nearest 100. Let's see where we can fit 278 on this number line.
07:46It is somewhere between 200 and 300. 278 is after the 50 mark, so we will round it up to 300.
08:01Now let's take another example, 450. We have to round 450 to the nearest 100. Let's see where
08:14we can fit 450 on this number line. It is somewhere between 400 and 500. The number
08:26is on the 50 mark that also is rounded up, so we will round it up to 500. See the figure.
08:38All the numbers between 0 to 49 are rounded down to 0 and 50 to 99 are rounded up to 100.
08:51100. Likewise, 100 to 149 are rounded down to 100 and 150 to 199 are rounded up to 200.
09:09So kids, we learned that in rounding off to nearest 100, we round the number to nearest 100.
09:18By rounding it down if it's below or before the 50 mark and round it up if it's above or after
09:27the 50 mark. Now we will learn rounding up the numbers to nearest 1000. Let's start with 400.
09:38See the number line. Where can you fit 400 on this number line? It is somewhere between 0 and
09:481000. Now we know there are always two options. Either we can round the number up or round it
09:58down. Depending on whether the number is after or before the midway mark and midway mark between
10:081000s is 500 and 400 is below or before the 500 mark, so we will round it down to 0.
10:21400 is more than 0. Let's take the next number. 890. We have to round 890 to the nearest 1000.
10:38See the number line. Where can you fit 890 on this number line? It is somewhere between
10:470 and 1000. 890 is above or after the 500 mark, so we will round it up to 1000.
11:01Now let's take another example. 1230. We have to round 1230 to nearest 1000. See the number line.
11:18Where can you fit 1230 on this number line? It is somewhere between 1000 and 2000.
11:29As 1230 is below or before the 500 mark, so we will round it down to 1000.
11:421230, 1000. Now let's take another example. 1689.
11:54We have to round 1689 to nearest 1000. Where can you fit 1689 on this number line?
12:09It is somewhere between 1000 and 2000. As 1689 is above or after the 500 mark,
12:21so we will round it up to 2000. Let's have a look at this figure to understand it more.
12:33All the numbers 0 to 499 are rounded down to previous 1000, that is 0,
12:43because they are below the 500 mark or the midway mark between 0 and 1000. All the numbers 500
12:53to 999 are rounded up to 1000, as they are on or above the 500 mark. Likewise,
13:06if you want to round off numbers 1001 to 1499, they will be rounded down to previous 1000,
13:16that is 1000, because they are below 500 mark. And numbers 1500 to 1999 will be rounded up to
13:30next 1000, that is 2000, as they are above the 500 mark. So kids, we learned that in rounding
13:41off the nearest 1000, we round to the number to nearest 1000 by rounding it down if it's below
13:50or before the 500 mark and round it up if it's above or after the 500 mark.
13:58Now you may go ahead and take a quiz to learn more. Bye-bye!