DazaKiwi wrote:if i was to reduce by 10,30,50,70 percent? what do I (A/12) * Y is there a formula to work out what number Y is?

To get 10%, 30%, 50%, or 70% you would use the corresponding formula above in my previous post. If you were to use twelfths or A/12, then you would be looking at 1/12 = 8.3%, 2/12 = 16.6%, etc.

To convert a percentage to a fraction put it over 100 and reduce. Or you could leave it as is and do the following:

To reduce A by 10%, keeping 90%: Set A equal to (A / 100) * 90

To reduce A by 20%, keeping 80%: Set A equal to (A / 100) * 80

To reduce A by 30%, keeping 70%: Set A equal to (A / 100) * 70

To reduce A by 40%, keeping 60%: Set A equal to (A / 100) * 60

To reduce A by 50%, keeping 50%: Set A equal to (A / 100) * 50

To reduce A by 60%, keeping 40%: Set A equal to (A / 100) * 40

To reduce A by 70%, keeping 30%: Set A equal to (A / 100) * 30

To reduce A by 80%, keeping 20%: Set A equal to (A / 100) * 20

To reduce A by 90%, keeping 10%: Set A equal to (A / 100) * 10

What all of these formulas do is they determine what 1/X is and then we multiply by the number of parts we wanted to keep. The fraction 9/10'ths is nine parts of one over ten total parts. We figure out what 1/10th is and then we multiple by 9 to keep 9/10ths or 90% of A. The math process I used to figure all of this out is based on multiplication with fractions.