Video: Finding the Sum by Breaking Apart to Add Hundreds First

Find the total by first adding the hundreds. 187 + 400 = _

02:25

Video Transcript

Find the total by first adding the hundreds. 187 plus 400 equals what?

In this problem, we’re adding a multiple of 100 to a three-digit number. The multiple of 100 is 400. And the number that we’re adding it to is 187. Now we can see that the way the calculation’s been written, the number 187 has been partitioned. Why is this?

Now we know that 187 is made up of one hundred, eight tens, and seven ones. And as we’ve said already, the number that we’re adding is a multiple of 100. It’s worth four hundreds. Now the question tells us to find the total by first adding the hundreds together. And we can do this by partitioning 187 so that we’ve got the hundreds separate so that we can add them. So we’ll take out our 100 ready to add. And this is why the number 187 has been partitioned in this way.

On the right-hand side, we have the 100 that we need to add. And on the left-hand side, we have the remainder, 87. We come back to this at the end. But to begin with, let’s add the hundreds. 100 plus 400 equals 500. But although we’ve added the hundreds together, we haven’t found the answer to our question because the number is still split up. We need to combine both parts back together again. So what is 87 plus 500?

Let’s combine our hundreds back with our tens and ones to find the answer. The answer has five hundreds, eight tens, seven ones. 87 plus 500 equals 587. One plus four equals five. So a number with 100 plus 400 equals a number with 500. 187 plus 400 equals 587.

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