Addition

Addition is one of the first things you learn when beginning math education. In
order to add, you must know how to count using traditional counting numbers (1,
2, 3, etc). Once you have a good understanding of counting, you will begin to add
numbers together. To start, we’re going to use one digit plus one digit examples,
and move on to harder examples.

Adding One Digit Plus One Digit Numbers

Adding one digit to another digit is the first kind of addition problem you’ll learn
how to complete. A basic addition problem looks like this:

2 + 1 = _____

In order to complete this problem, you would first count to two, and then count
one more (adding it), and get to three. If you were to look at it with pictures
instead of numbers, it would look like this:

For beginners, it may be easier to draw dots and then count them all together, like
we did for this one. Let’s try this again. Here’s the problem, in numbers and in
pictures:

Now, count up the dots. How many did you get? You should have gotten five in the
end. If you didn’t, go back and re-count them.

Adding Two Digit Plus One Digit Numbers Without Carrying

Once you can add simple numbers together, you’ll move on to adding two digit plus
one digit numbers. A two digit plus one digit problem would look like this:

In order to complete this problem, you’re first going to add the ones’ columns together.
For this problem, you’d be adding together 5 + 2. You write the answer to this part
in the ones’ column under the answer bar. Then, you move on and add the tens’ column
together. In this problem, the only number in the tens’ column is 1, so you would
bring 1 down and write it in the tens’ column of the answer.

Then, you’re done! Here’s the work for the problem:

Step 1:

Step 2:

Now, we get our final answer of 17.

Adding Two Digit Plus One Digit Numbers With Carrying

After you add two digit plus one digit numbers for a while, you’ll run into a problem
where you have to carry a number. This happens when you get an answer of 10 or more
when you add the ones’ column together. For example, if your ones’ column said 9+3,
that gives you 12, and you’d need to carry. In order to carry, you need to follow
three steps very carefully.

First, after you’ve added and gotten the number, you need to split the number up
into two separate digits. You’re not going to write anything yet; you do this step
in your head. For example, if you got 12 for your answer to the first part of the
problem, you would look at it as 1 and 2 (two separate digits).

Second, you’re going to take the ones’ digit of the number you just split up, and
write it in the ones’ column of your answer. (This should seem normal after doing
addition without carrying).

Last, here’s the different step: you’re going to take the tens’ digit of the number
you just split up, and write it at the top of the tens’ column in your addition
problem.

Congrats, you’ve carried! Now let’s see what it looks like in the problem itself:

Now you need to finish the addition problem. All you have left to do is add together
the numbers in the tens’ column now. Notice that after you’ve carried, there are
now 2 numbers in the tens’ column. In this problem, they are both ones. You would
add these two numbers together, and place the answer in the tens’ column of the
answer. It would look like this:

Now you have a final answer, 22.

Let’s try this a couple more times to make sure you understand.

Go ahead and try this problem on your own. Remember to split up the answer to the
addition of the ones’ column, and put the ones’ digit in the answer while carrying
the tens’ digit up to the next column. We’ll show this one more time, but after
that we’re not going to write it out.

Adding Two Digit Plus Two Digit Numbers Without Carrying

More advanced addition problems will ask you to add two digit plus two digit numbers.
A problem adding together two two-digit numbers looks like this:

This may look a little harder than before, but don’t worry! It’s not too bad. You
just have to remember to do it in the right order. First, add together the ones’
column, and write the answer beneath the answer bar, like this:

Then, move over to the tens’ column and write that answer in the tens’ column beneath
the answer bar, like this:

The solution would look like this:

Did you get 55? If not, re-add each column to see where your mistake is. Remember
to add each column separately in order to get your answer. Your final answer for
this problem is 55.

Adding Two Digit Plus Two Digit Numbers With Carrying

Now that you know how to add two digit numbers together, we’re going to practice
doing it when you have to carry a number. It works very similarly to the carrying
shown previously. Here’s a problem to start with, and we’ll go through each step
of solving it.

Start this as you would a normal addition problem, with the ones’ column. Notice
when you add the ones’ column together that you get a number higher than ten, which
means you have to carry. You’re going to carry the same way as we showed in
Adding Two Digit Plus One Digit Numbers With Carrying. Split up the number
and write the ones’ digit under the ones’ column beneath the answer bar, and write
the tens’ digit above the tens’ column in the addition problem. These steps look
like this (the ones’ column is circled in red, and the number in red at the top
of the tens’ column is the number that was carried).

Now, you can go ahead and add the tens’ column together. Notice that now there are
three numbers in the tens’ column that you must add together, 1 + 3 + 2. Here’s
the rest of the solution:

Thus, our final answer is 61.

Let’s try one more example that’s a little bit harder. Here’s the problem:

First, add the ones’ column together. Place the ones’ digit of the answer beneath
the answer bar in the ones’ column, and the tens’ digit of the answer above the
tens’ column in the division problem.

Now, once again, you have 3 digits in the tens’ column to add together, 1 + 6 +
8. When you add these together, you get 15. Next, you simply write 15 in front of
the 6. Now, you have 6 in the ones’ column, 5 in the tens’ column, and 1 in the
hundreds’ column. Your solution looks like this (we’ll put the 15 in red so you
can see how it lines up):

Thus, our final answer is 156.