Question

17,18,19,20,21,22,23,24. 1.From the list of numbers write down a number that is a factor of 20. 2. From the list of numbers in the list, which is a multiple of both 3 and 7

Answer 1

Problem 1

Answer:  20

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Explanation:

The factors of 20 are 1,2,4,5,10,20

They are numbers that pair up to multiply to 20. For instance, 5*4 = 20. We only focus on whole numbers.

In the list given to us, we see that only 20 is a factor of 20. Something like 17 is not a factor of 20, and so on for the other values.

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Problem 2

Answer:  21

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Explanation:

List out the multiples of 3 to get {3, 6, 9, 12, 15, 18, 21, 24, 27, 30, ...}

The stuff in bold are values found in the original list.

Now list out the multiples of 7 to get {7, 14, 21, 28, 35, 42, ...}

We can see that only 21 is found in both lists of multiples we wrote out.

Note how 3*7 = 21, which is not a coincidence.