A number has exactly eight factors. Two of the factors are 8 and 20. What are all the factors of the number?
1 Answer
Jun 24, 2017
1, 2, 4, 5, 8, 10, 20, and 40
Explanation:
If 8 is a factor, then so are 2 and 4.
If 20 is a factor, then so are 5 and 10.
1 must be a factor by default.
So the 8 factors are:
1, 2, 4, 5, 8, 10, 20, ??
Factors come in pairs, and their products always add up to the number itself, which is a factor. The pairs are the first and last, second and second last, etc.
In this case, all the pairs multiply to 40:
5 xx 8 = 40
4 xx 10 = 40
2 xx 20 = 40
So the last factor must be 40 (the number in question itself).
Final Answer