Oh, that's a happy little question! Let's take a look at 90 and see which number doesn't fit in. Every number that can divide evenly into 90 is a factor, so we just need to find the one that doesn't quite fit the pattern. Can you see which number doesn't belong in this peaceful little group of factors?
90
180
Every positive number is the greatest factor of itself.
They are 45, 90, 135, 180, 225, 270, 315, 360, 405, and 450.
No, 90 is a multiple of 18. 18 is a factor of 90.
If 21 is a multiple of the number, the number cannot have 90 as a factor.
The greatest factor of any number is the number itself.
6, 18, 30, 90
Every number is the highest factor of itself.
9
obviously, its highest common factor is the number itself. so the answer here is 90.
That would be 15. Only a number ending in five would be a factor of 75. 45 is not. 35 is not. 25 is not. 15 is, and it also is a factor of 90. This makes it the highest common factor of 75 and 90, although it is not a prime factor.
90
10
The greatest common factor (GCF) refers to a factor that is COMMON to two or more numbers. You have only one number in the question! The greatest factor of any number, such as 84+16 = 90 is the number itself, ie 90.
180
Choose any number except zero for the first factor. Then divide 90 by this factor to get the second factor.