Question Video: Using Repeated Addition to Multiply by 2, 5, or 10 | Nagwa Question Video: Using Repeated Addition to Multiply by 2, 5, or 10 | Nagwa

Question Video: Using Repeated Addition to Multiply by 2, 5, or 10 Mathematics

There are 4 monsters. Each monster has 2 horns. How many horns are there? Each monster has 5 eyes. How many eyes are there? Each monster has 10 teeth. How many teeth are there?

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Video Transcript

There are four monsters. Each monster has two horns. How many horns are there? Two plus two plus two plus two equals what. Each monster has five eyes. How many eyes are there? Five plus five plus five plus five equals what. Each monster has 10 teeth. How many teeth are there?

And we can see an addition that has four empty boxes. And we need to find the answer. So to begin within this problem, we’re told that there are four monsters. And we should be pretty thankful that we can’t see any pictures of these monsters because they sound pretty scary. Each monster has two horns, five eyes, and 10 teeth. And we need to use this information to find the number of horns, the number of eyes, and the number of teeth.

So in the first part of the question, we read that each monster has two horns. This means that there are one, two, three, four groups of two horns. These are four equal groups because we know that each monster has the same number of horns. That’s why we can see how to find the answer here by adding the number two four times: two plus two plus two plus two. We know that two plus another two equals four. And if we add another two to four, we get six. And finally, six plus another two makes eight. There are eight horns altogether.

Next, we’re told that each monster has five eyes. So we know there are one, two, three, four groups of five eyes. And, you know, because our four groups are equal, we can again find the answer by adding the same number four times. This time it’s five because there are five eyes: five add five add another five add another five. Let’s get adding. To begin with, let’s add our first two fives. Five add five equals 10. Now if we add our next group of five, 10 plus five more is 15. And five more than 15 is 20. There are 20 eyes altogether.

In the final part of the question, we’re told that each monster has 10 teeth. So we know what this means by now, don’t we? It means there are four equal groups of 10 that we need to count. And we can use this information to complete our addition. To find the answer, we need to find the total of 10 plus 10 plus another 10 plus one more 10. What we’re doing here is repeating the same addition again and again, aren’t we? 10 plus another 10 equals two 10, which is the same as 20. 20 plus one more 10 gives us a number with three 10s in it; it’s 30. And 30 plus one more group of 10 makes four groups of 10, which is 40. There are 40 teeth altogether. Thankfully, they’re smiling.

We’ve added the same number four times here to help us find each answer. We know that each monster has two horns. And so to find the total number of horns, we needed to add together two and two and another two and one more two. There are eight horns altogether. Because each monster has five eyes, we just needed to add together the number five four times. The total number of eyes is 20. And then finally, because we’re told each monster has 10 teeth, this is the same as four equal groups of 10. We just added the number 10 four times. The number of teeth there are altogether is 40.

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