# Question Video: Taking Away a Number from Itself and Identifying the Related Subtraction Sentence Mathematics • 1st Grade

There are 4 balloons, and all of them have popped. How many are left? Write the equation that explains this situation. [A] 4 − 0 = 4 [B] 5 − 4 = 1 [C] 4 − 4 = 0 [D] 5 − 5 = 0

02:45

### Video Transcript

There are four balloons, and all of them have popped. How many are left? Write the equation that explains this situation. Four take away zero equals four, five take away four equals one, four take away four equals zero, or five take away five equals zero.

The first piece of information we’re told in this problem is that there are four balloons, although perhaps we should say there were four balloons because we’re then told that all of them have popped. And we can see this in the picture. Now, there’s a very important word in this sentence and that’s the word “all.” We’re told, all of them have popped. What does the word “all” mean? Well, it means every single one of them. And in this question, the word “all” represents the number four. We had four balloons and all of them have popped. So that means four of them have popped. And of course, we can see if we count the remains of the balloons in the picture that four of them have popped.

And we’re asked how many are left. Well, perhaps we know what the answer is already. But let’s model the question using counters just to be sure. These four counters can represent our four balloons. Now, let’s take away counters to represent the balloons popping. Remember, we need to show that all of them have popped, so we need to take away one, two, three, four. Four take away four leaves us with nothing. And so if all of the balloons popped, we’re left with zero.

The next part of the problem asks us to write the equation or the number sentence that explains the situation. Which of these number sentences shows us that there will be zero balloons left if we pop all four of them? Well, if there is zero balloons left, then we’re looking for an answer that is zero. So that means we can ignore the first and the second number sentences here. Both of our two remaining number sentences have an answer of zero. But which one is correct? Four subtract four equals zero or five subtract five equals zero. There were four balloons and all four of them popped. So the equation that explains this is four take away four equals zero. When we subtract all of a number from itself, we’re left with nothing or zero.

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