Video: Determining the Repeated Addition Expression Equivalent to a Given Multiplication

Pick the expression that equals 10 × 6.

03:07

Video Transcript

Pick the expression that equals 10 multiplied by six. And then we’re given five possible answers. All of them involve adding 10 lots of times. But which one is the same as 10 multiplied by six?

Let’s start by thinking about what’s the same and what is different about the multiplication and the possible answers. Well, they both contain the number 10. But the calculation in the question involves a multiplication symbol, whereas each of the answers involves adding the number 10 lots of times. You could say we’re adding 10 multiple times.

Multiple addition is the same as multiplication. So which one of our additions is the same as multiplying 10 by six? Let’s draw an array to help us. So we can draw 10 rows with six squares in each row. And this represents the calculation 10 multiplied by six which we know equals 60. We can think of this as six groups of 10. So whilst multiplying 10 by six is a quick way to find the answer, we can also find the answer by adding 10 six times.

Which expression shows us adding 10 six times? Let’s look at the first one. One, two, three, four, five. 10 plus 10 plus 10 plus 10 [plus 10]. Five lots of 10 is the same as 10 multiplied by five. So we need to find an expression with one more 10 in it. Which expression looks like it has one more 10 in it?

Well, the third one looks slightly longer. Let’s count the 10s. One, two, three, four, five, six. Six 10s are the same as 10 multiplied by six. And we can quickly check that the multiplication and the addition are the same. 10 plus 10 is 20 add another 10 is 30 add another 10 is 40. Five 10s are 50. And then when we add our sixth 10, we get a total of 60. 10 plus 10 plus 10 plus 10 plus 10 plus 10 equals 60. And so the expression that equals the same as 10 multiplied by six is the one where we add 10 six times.

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