Possibly Correct, Could someone tell me for sure
First we factor 90 into primes 3*3*5*2
I thought of this as a combination problem with a duplicate choice 4! / 2 !
4! because I have to put the numbers in order A*B*C*D
2! because I have a duplicate choice (3)
Can anyone tell me if this will work for other situations?
or did I just confuse myself and everyone else?Alternatively, I write these questions out starting with the largest and smallest factor
(I am using the .... to show that I write them a good distance apart on my scratch paper.)
1 .............................................................................................................. 90
next
1,
2,...........................................................................
45, 90
1, 2, 3 30, 45, 90
1, 2, 3, 5, 18, 30, 45, 90
If find that doing things this way prevents me from having duplicates and quickly gets me to a situation where I know I have covered all the possibilities.
This method is really only good for number less than 100. For example if you had 87452, it might take too much time to do this.