I need to change what I multiple by based on the entered number.

If the entered number is 1 to 3, I need to multiply by .25
If the entered number is 4 to 6, I need to multiply by .5
If the entered number is 7 to 9, I need to multiply by .75
If the entered number is 10 to 12, I need to multiply by 1 and so forth.

so if I enter 5 in A6, it will multiply 5 by .5 and put the result in A7

Any suggestions?