Addition and Subtraction

Solving Problems

Now that you know how to write addition problems, let's solve some. When you're just getting started, you might find it easier to use counting to solve problems.

For instance, can you use counting to write and solve this problem?

With that problem, you were able to count the objects you were adding. In real life, some people like to count with their fingers. Other people use small objects, like buttons or pennies. Others might make small marks on a piece of paper. When you're learning to add, it's OK to count! The more you practice, the easier it will get to add without counting.

Ways to Count

Let's look at two ways to solve addition problems with counting. First, we'll count with objects.

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  To count with objects, use the objects to show each number in the expression. Let’s try it with this expression, 2 + 3.

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  The first number is 2, so we'll need 2 objects.

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  The first number is 2, so we'll need 2 objects.

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  The first number is 2, so we'll need 2 objects.

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  The next number is 3. We'll grab 3 more objects.

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  The next number is 3. We'll grab 3 more objects.

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  The next number is 3. We'll grab 3 more objects.

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  Now we can finish our equation. All we have to do is count!

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  Now we can finish our equation. All we have to do is count!

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  Now we can finish our equation. All we have to do is count!

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  Now we can finish our equation. All we have to do is count!

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  Now we can finish our equation. All we have to do is count!

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  There are five objects total, so our answer is 5

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  To finish, we'll write 5 to the right of the equals sign.
  
   

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Number Lines

Another way to solve addition problems is to use a number line.

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  Counting with a number line only takes a few steps.

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  To use a number line, you count by moving right one number at a time.

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  To use a number line, you count by moving right one number at a time.

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  To use a number line, you count by moving right one number at a time.

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  Let’s practice adding with a number line. We'll try this problem, 5 + 2.

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  We need to start counting from the first number in our expression.

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  Here, that number is 5.

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  So, we start counting at the 5 mark on the number line.

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  Next, we’ll count right from the second number in our expression.

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  We’ll move right 2 times.

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  We’ll move right 2 times.

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  We’ll move right 2 times.

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  We landed on 7. This means that 5 + 2 is 7.

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  We'll write 7 to the right of the equals sign. Our equation is complete!

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Solve these equations. Try using the number line to help!