# Video: Solving Word Problems by Adding Two Whole Numbers

A field has 3977 mango trees and 3157 orange trees. How many trees are there in total?

03:18

### Video Transcript

A field has 3977 mango trees and 3157 orange trees. How many trees are there in total?

The words in total here tell us that we need to add to find the answer. There are 3977 mango trees and 3157 orange trees. The answer to our problem is going to be the answer to 3977 plus 3157. We can add these two numbers together using column addition.

And the first thing we need to do is to write each number so that the digits appear in the correct place. In other words, the thousands, the hundreds, the tens, and the ones digits are in columns. This allows us to add the ones, the tens, the hundreds, and the thousands separately.

So, let’s begin by adding the digits in the ones column. Seven ones plus seven ones equals 14 ones. But we can only write one digit in the ones place. So, how can we express 14 ones? We can exchange 10 of our 14 ones for one ten. So, we can write one ten and four ones.

Now, let’s add the digits in the tens column. Seven tens plus five tens equals 12 tens. And we’ve also exchanged a 10 as well. And include this, we have 13 tens. Again, we can’t write a two-digit number in this column. So, we can exchange 10 of our 13 tens for one hundred. 10 tens are the same as one hundred. So, we can express our 13 tens as one hundred, that we’ve exchanged, and three tens.

Now, let’s add the digits in the hundreds column. Nine hundreds plus one hundred, also the one hundred we exchanged, makes 11 hundreds in total. This is another two-digit number. We’re going to need to exchange again. We’ll take 10 of our 11 hundreds and exchange them for one thousand. 10 hundreds are the same as one thousand. And so, we can express our total of 11 hundreds as one thousand and one hundred.

Finally, let’s add the thousands digits. 3000 plus 3000 plus the 1000 we’ve exchanged equals a total of 7000. We’ve used column addition to help us add our two four-digit numbers together. If a field has 3977 mango trees and 3157 orange trees, we can find the total number of trees by adding these two numbers together. And an efficient way to do this is by using column addition. The total number of trees in the field is 7134.