Lesson Video: Multiplying by 1 and 0 Mathematics • 3rd Grade

In this video, we will learn how to multiply whole numbers by 0 and 1.

07:17

Video Transcript

Multiplying by One and Zero

In this video, we will learn how to multiply whole numbers by zero and one.

Let’s start by thinking about what happens when we multiply a number by one. This model shows six egg cups. And each egg cup contains one egg. And we can say that six times one equals one. What do you notice about this number sentence? Well, we started with the number six, and the product is six. When we multiplied six by one, the product or the result is six. So we could say that when we multiply a number by one, the product or the result we get is that number. Let’s test this statement by investigating what happens when we multiply different numbers by one.

In this multiplication table, Sophia colored all the multiples of one green. Use the table to finish the following sentence. When you multiply any number by one, the product is zero, one, or the same number.

In this question, we have to investigate what happens when you multiply any number by one. Is the product zero, one, or the same number? And we’re given this multiplication table to help. Sophia’s colored all the multiples of one green. So we can see that the product of one times one is one. Two times one is two. Three times one or one times three is three. Four times one is four. And five times one is five.

What did you notice? When we multiplied one by one, the product is one. When we multiplied two by one, the product is two. Three multiplied by one is three. Four multiplied by one is four. And five multiplied by one is five. So when we multiply any number by one, the product is the same number.

We call this rule the identity property of multiplication. When you multiply a number by one, the product is the same number. Let’s investigate what happens when you multiply a number by zero.

When we multiply, we can think about equal groups of dots. Four groups of two dots equals eight dots; four times two equals eight. How many dots would there be if you drew zero groups with eight dots in each group? Find the missing number: Zero times eight equals what.

This is a two-part question. In the first part, we have to think about how many dots there would be if we had zero groups with eight dots in each group. When we’re multiplying, we can think about equal groups of dots to help. This model shows four groups of two. And four times two is eight. This model shows four groups. If we draw no groups or zero groups, there would be no dots. If there are no groups, there are no dots, which means that zero multiplied by eight equals zero. If four groups of two dots equals eight dots and four multiplied by two equals eight, then no groups with eight dots equals zero and zero multiplied by eight equals zero.

We call this the zero property of multiplication. When you multiply a number by zero, the product is zero.

Matthew started with 12 stars in three groups of four. Three groups of four. Three times four equals 12. Remove one group at a time. Find the missing numbers. Two groups of four, two times four equals what. One group of four, one times four equals what. Zero groups of four, zero times four equals what.

Matthew started with 12 stars in three groups of four. We have to remove one group of four at a time to find the missing numbers. We know that three times four is 12. So to find two groups of four, we just need to take away one group of four. What is four less than 12? Two times four is eight. Four less than 12 is eight.

If we take away another four, we will have one group of four, which is four. One group of four or one times four is four. And to find zero times four, we just need to take away another group of four. Four take away four is zero. Zero times four equals zero.

Matthew started with 12 stars in three groups of four. And he removed one group at a time. Two groups of four or two times four equals eight. One group of four or one times four equals four. And zero groups of four equal zero.

So what have we learned in this video? We’ve learned that when we multiply a number by one, the product is that number. We call this the identity property of multiplication. We also learned that when we multiply a number by zero, the product is zero. And we call this the zero property of multiplication.

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