Question Video: Subtracting Three-Digit Numbers Using Partial Difference | Nagwa Question Video: Subtracting Three-Digit Numbers Using Partial Difference | Nagwa

Question Video: Subtracting Three-Digit Numbers Using Partial Difference Mathematics • Second Year of Primary School

Find the difference by first subtracting hundreds. 873 − 500 = _

03:20

Video Transcript

Find the difference by first subtracting hundreds. 873 take away 500 equals what?

The first number in our subtraction, 873, has been broken down into two parts. 873 is the same as 800 and 73, but it seems to be written the wrong way around. Normally, we tend to write 800 in the first circle and then 73, the small amount, in the second circle. Why is the number 800 on the right? Well, it’s because we need to find the difference between 873 and 500 by subtracting hundreds. In other words, we can take away 500 from the hundreds part of 873.

So to start with, we need to work out the answer to 800 take away 500. 800 is made up of eight in the hundreds column, zero tens, and zero ones. And 500, the number we’re taking away, is made up of five in the hundreds column, and again zero tens, and zero ones. This is why the question asks us to subtract just the hundreds. This is the only column we need to think about. So we’ll start with 800, and let’s take away 500. Watch how the digit changes. We’ll take away 100, then 200, 300, 400, 500. We started with eight 100s. We took away five 100s. We’re now left with three 100s. 800 take away 500 equals 300.

But, this isn’t quite the answer to our question. If you remember at the start, we broke the number 873 into two parts. We said those parts were 73 and 800. Now by taking away 500, the 800 part has now become 300. And so, we can combine the parts to find the answer. 73 plus 300 or, if you look at it the other way around, 300 plus 73 equals 373. We found the difference by partitioning 873 into a multiple of 100, which was 800, and 73. We then subtracted the hundreds and then combined the two parts back together again to find the answer. 873 take away 500 equals 373.

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