Video: Solving Word Problems Requiring Addition of Three Whole Numbers Whose Sum Is Less Than 20

Madison has 1 dog, 7 fish, and 2 rabbits. She has 1 + 7 + 2 pets in total. How many pets does she have?

02:10

Video Transcript

Madison has one dog, seven fish, and two rabbits. She has one plus seven plus two pets in total. How many pets does she have?

In this problem, we need to find the total number of pets that Madison has. We’re told that she has one dog, seven fish, and also two rabbits. We know that, to find the total number of pets, we need to find the answer to one plus seven plus two. When we add several small numbers like this, it’s always good to look at them and to see how can we combine them to add them more quickly. We can add them in any order. And they’ll still make the same total.

One way we could find the answer is to add one and seven first. Let’s start with the larger number and then add one. Seven and one equals eight. What is eight add two? Well, by adding seven and one first, we’ve made a number that pairs with two. Eight plus two is a pair of numbers that make 10.

Let’s check our answer by adding in a different order. We know that one plus two equals three. Why would we add these two numbers first? Well, by making a total of three, we’ve now got a pair that goes with the remaining number. Three and seven pair together to make 10. So no matter which order we add the numbers together, we’ll always get the same answer. And we found our answer by looking for pairs that we could use to help us.

One plus seven plus two equals 10. Madison has 10 pets in total.

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