How do I see where my schedule conflicts?

I have uploaded a dummy excel sheet as an example. In this sheet you will see four different schedules, each one representing a given activity. I have my schedule for when my all day book club meets, for what days my all day men's softball games take place, my all-day science classes, and my all day math classes.

In column A is the Math class schedule, C = book club schedule, E = softball, G = science class schedule.

How do I see how much easy schedule conflicts with the others?

In other words, I want a formula to compare the the dates in Column A to the ones in C, E, and G, and see how many dates conflict for each one. So I want a number, how many dates between column A and column C conflict, how many between A and E conflict, how many between A and G conflict. If the formula also tells me which days conflict, even better, but not mandatory.

Then I want to do the same thing for column C. How many days in column C's schedule conflict with column A's? What about C and E? C and G?

That's what I really need to do, with a formula I can adjust in case I add more schedules.

Can someone please help with this? Thank you very very very much!

Thanks hamilton, I think its working? I mean for A:E, A:I, etc, there are rows of 01001001. Are those saying which dates overlap and which dont? As in every time it says 1, it means there is 1 overlap, and every time 0, none?

If thats the case, then its working. The only problem is I need to be able to add up the total. So when I tried to do =sum for the A:E column, for instance, instead of adding up all the overlaps, it just gave me a date. Like it's still adding the numbers up as dates even when you "sum." How do I get a total for number of overlaps per schedule comparison?

Also hamilton, a very important question, how do I apply this to larger schedules? Can you tell me how it works so I can do it with many more schedules? I need to be able to do this with as many as 15, 20, maybe 25 or more schedules. I have the time tomorrow I just need to know how to do it.

Okay hamilton I think I understand how the formula works, and how to add it up. The only problem Im having now is that when I do a lot of schedules, it will take too long to manually input the new formula for each cell.

Basically, when you compared I-A, I-E, and I-M's schedules, you used the formulas....

=COUNTIF($A$2:$A$83,$I2)
=COUNTIF($E$2:$E$83,$I2)
=COUNTIF($M$2:$M$83,$I2)

So every cell over, the formula changes. When you're comparing I and A, inside the brackets it says $A$2 and then I so and so.

Then when you compared E and I, E and I were inside the brackets.

The problem Im having is that I want to keep doing this, copy and paste the formula to say 20 more cells to the right, and have the formula adjust to the new cell its in. What's happening now is, say if I tried to copy the A-I formula into the next two cells, this is what I get.

=COUNTIF($A$2:$A$83,$I2)
=COUNTIF($A$2:$A$83,$I2)
=COUNTIF($A$2:$A$83,$I2)

The A-I formula just copies itself three times, without adjusting the formula for the new cells.

How do I fix this problem?

How do I fix this problem?

By checking XL's help on "absolute and relative addressing"