Hi Friends,
Ok, here's another silly problem that I can't figure out.

(Oops, I didn't mean for that to be so big!)

The result I'm trying to achieve is the 2 (USA) football shaped areas, where the 3 circles overlap, the darker blue areas, standing alone. When I select 2 of the circles and choose Intersection, I do get one football shape. But when I select all 3 circles and choose Intersection, everything disappears.

In the full image, there are 5 more circles, creating a circle of 8 circles, so to speak. I realize I could use layers, and go around selecting each 2 adjacent circles, and finally end up with 8 of the football shapes arranged in a circle, looking maybe something like a flower. But to me, it would seem easier to select all 8 circles and click Intersection, and do it all in one step. But if I select any more than 2 circles at a time, click Intersect, all of the circles disappear.

What's happening here? What am I missing that's causing them to disappear, and how do I get my desired results? Thank you very much for your help

Duplicate (Ctrl+D) the middle one. Then intersect one copy with the left circle, and the other copy with the right circle.

For the full eight circles, you need to duplicate all eight, and intersect them in pairs.

You can also try doing it once and cloning the object resulting object to create the circle of footballs you're after. Give me a minute and I'll upload an image/tut.

Just to confuse things you could also do it using clips I recommend you do what llogg1 is suggesting though.

Hhm....
Ok, so it sounds like I have to do them one pair at a time, whether by clone, clip or duplicate. I look forward to Nogg1's info.

But I still don't understand why. Can someone explain why it doesn't work with more than one object? Because I did read this in the Advanced Tutorial:

The Difference and Exclusion commands can only apply to two selected objects; others may process any number of objects at once.

Oh! I actaully didn't think about why your objects were completely disappearing.

Your quote is correct, you can perform an intersection on multiple objects and in your example it produces no objects at all. Why? Because it calculates the intersection of all three circles - two of your circles don't overlap each other which means there is no intersection. If each circle overlapped the other two circles the intersection would successfully create a new shape.

I hope that makes sense - I can't draw a diagram right now.

If you want to do what you are asking, do a union on the two circles that don't overlap then do the intersection.

Ah, I managed to think of good analogy from year 8 maths

We'll label your circles from left to right A, B and C and imagine they represent population of people.

Your diagram would show that some of population A is in population B. Also, some of population C is in population B. And when calculating an intersection of all three populations we ask the question, how many people are in populations A, B and C? The answer is none, since A and C don't overlap. Which is why Inkscape doesn't create your two footballs. You need to treat population A and C as one first (i.e. union).

Aaaahh....I think I understand. At least partly anyway. It still doesn't completely make sense, but I still have SO much to learn about this program!

I'll work with the ideas everyone has offered, and I'm sure things will make more sense as I work through it. I just had no idea where to start troubleshooting before. So THANKS everyone for your comments. I think I have an idea how to do this quickly, without taking the Intersection of each pair (8 individual operations). If it works out, maybe I'll post what I did.

Anyway, thanks again. You guys are the best!

Yay, it worked!
It's probably simple to most of you, but for any potential future readers who might find it helpful, here's how I did it:

Basically there are 2 sets of non-intersecting circles. In the example below, I colored them with purple strokes, and black strokes.

So I selected all the purple circles and clicked Union. Then I did the same for the black circles. Then I selected the union of purple circles and the union of black circles, and clicked Intersection. And ta-daaaa!

Thanks again for your help

Sorry it took me so long. I'm glad your method worked so well for you though. FYI you can still use the cloning function to speed up placement of your circles using the method in my tut below.

Sorry it took me so long. I'm glad your method worked so well for you though. FYI you can still use the cloning function to speed up placement of your circles using the method in my tut below.
http://files.myopera.com/llogg/files/footballflower.svg