To find out the answer of the addition problem, add up two known numbers.

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How do we solve the problems and find the total number of objects in several groups? It is the addition, so we add the numbers of objects from one group to the number of objects from the other. The sum of these numbers denotes the total number of all objects.

To solve it we need to review all the known data. These are two numbers - the number of items in the first group and in the second. Here is a problem: There were 12 children on the playground. Then 5 kids joined them. How many children are there now?

What numbers do we know? The number of children on the playground from the very beginning - 12. And the number of kids that came later - 5. These are two numbers that we will add up: 12 and 5.

Let’s write down this math condition using signs (12+5) and then find its value. To add 12 to 5, we need to find the sum of ones and remain the number of tens the same. The number that is in the ones place in the number 12 is 2. Let’s add up 2 and 5. 2+5=7. We got 7 ones. Let’s write this number in the ones place on the right of the number 1. Thus, we got 17. It is the answer to our problem. There were 17 children on the playground in total.

By adding up two known numbers, solve all the addition problems.

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