Help!

[Xeric]

Hey guys. I'm sure these two programs are really simple, but I'm in my first java programming class and I don't have any programming background. I think I missed the class when we went over this stuff. Anyways, I have to write two programs for homework.

1) Write a program that outputs the product of all the integers between 3 and 7, inclusive, that is, 3*4*5*6*7. Use while loop for this program.

2) Write a program that counts how many multiples of 7 are between 33 and 97, inclusive. Use for loop for this program.

I know how to use the for and while loops and everything, but I'm not sure how to go about writing these programs. Any help would be greatly appreciated. Thanks!

[LacrosseB0ss]

if you use a for loop for the first one it's very simple. Say for x=3 to x<8. Then you can use x inside the loop. total = total*x.

for the second, again use a for loop starting @ 33 and go until 97. check each numebr using mod. If mod = 0, it's a mutiple. Use a counter if you need to output the number at the end.

[Xeric]

Well, for the first one it HAS to be a while loop.. that's the assignment. Also, I don't exactly follow what you're saying on the other one either. I'm very new to this. What is mod?

[Xeric]

This is what she told me when I emailed to ask about it.

1)Finding the product of numbers between 3 and 7, is similar
to finding the sum of n numbers program that we did in
class.

For this program you are supposed to use a while loop. First
you need to identify the condition that will make the while
loop execute. After that apply the logic similar to one that
we did toady in class( instead of sum its going to be
product , so you need to multiple).


2) For the second program you are supposed to use a for
loop, create a loop that iterates through all numbers
between 33 and 97 . Then for each number check if it is
divisible by 7. if true update the 'count of numbers
divisible by 7'. Otherwise just continue with the loop.

[Ganon11]

All right, break it down, just like your teacher said. For the first problem, your first step will be identifying the end condition. Well, you want to calculate numbers between 3 and 7, so it makes sense that you want to start at 3. Start an integer variable (index) and set it to 3 before your loop. If you know you're going to be increasing this variable each time, then you want it to stop when it's larger than 7. In other words, you only want your while loop to execute while the variable is less than 8.

Now, you're multiplying and storing this value into a variable, so you should start another integer variable (sum) before your loop and set it to 1. This way, when your loop first executes, you can say sum = sum * index; and will get 3 to start.

Finally, inside your loop, all you will be doing is two things:

1) Update sum by multiplying it by index
2) Update index by adding 1

Good luck!

[LacrosseB0ss]

My apologies xeric. Mod is a mathematical operation which returns the remainder of a division problem. The syntax for this is # % # and the answer will be the remainder.

Example:
4 % 2 = 0
5 % 2 = 1
etc

In your case you would use # (depending where in the loop you are) % (mod) 7 and check if it is 0. If it is, that number is a factor of 7. Hopefully this helps.