# Can someone explain?

How many times is the print statement executed, wehre i,j,k ∈ Z? Explain

For i := 1 to 12 do

For j :=5 to 10 do

For k:=15 downto 8 do

Print (i-j)*k

-
OMG! When you don't know what to do, try multiplying... –  jpalecek Oct 10 '12 at 0:27
Welcome to math.SE: since you are new, I wanted to let you know a few things about the site. In order to get the best possible answers, it is helpful if you say in what context you encountered the problem, and what your thoughts on it are; this will prevent people from telling you things you already know, and help them give their answers at the right level. If this is homework, please add the homework tag; people will still help, so don't worry. Also, many find the use of imperative ("Prove", "Solve", etc.) to be rude when asking for help; please consider rewriting your post. –  Julian Kuelshammer Oct 16 '12 at 19:34

Start inside and work out. The innermost loop executes once for each value of $k$ from $15$ down to $8$; that’s $15-7=8$ values, so the print statement is executed $8$ times every time the innermost loop is entered.
Now how often is the innermost loop entered? Once for each value of $j$ from $5$ to $10$, i.e., $10-4=6$ times. That is, every time the middle loop is entered, the innermost loop runs $6$ times, so the print statement is executed $6\cdot8=48$ times.
@BrianM.Scott: Is the print command executed when $k=8$? Or is it possible to stop the process when $k=8$? Will this depend on the program language? –  Sigur Oct 10 '12 at 1:44
@Sigur: I’m assuming that downto works like to, which in every language that I’ve used includes the limit. –  Brian M. Scott Oct 10 '12 at 1:47