Question

A certain number has exactly eight factpors

Answer 1

Answer:

1, 2, 4, 5, 8, 10, 20, and 40

Step-by-step 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

×

8

=

40

4

×

10

=

40

2

×

20

=

40

So the last factor must be 40 (the number in question itself).

Final Answer

Answer 2

Given that a certain number has exactly

eight factors including 1 and itself two of

its factors are 21 and 35.

Since 21 is factor of that number then

factors of 21 will also be factors of the

required number.

factors of 21 are 1,3,7,21.

So we found two more factors 3 and 7

Since 35 is factor of that number then

factors of 35 will also be factors of the

required number.

factors of 35 are 1,5,7,35.

So we found one more factor "5" which

was not on the list.

Now LCM of 21 and 35 will also be a

factor which is 105.

Let's collect all factors. we get:

(1,3,5,7,21,35,105)

they are 7 in total so we need one more

factor which can be multiple of 3 and 5

which is 15

New list is (1,3,5,715,21,35,105)

Now we have total 8 numbers in the list

so final answer is 105.

(I have answer for A certain number has exactly eight factors including 1 and itself two of its factors are 21 and 35 the number )