Multiple Condition Coverage is also known as Condition Combination Coverage.
In Multiple Condition Coverage for each decision all the combinations of conditions should be evaluated.
Lets take an example:
Here we have 2 Boolean expressions A and B, so the test set for Multiple Condition Coverage will be:
TEST CASE1: A=TRUE, B=TRUE
TEST CASE2: A=TRUE, B=FALSE
TEST CASE3: A=FALSE, B=TRUE
TEST CASE4: A=FALSE, B=FALSE
As you can see that there are 4 test cases for 2 conditions. Similarly there will be 8 test cases for 3 conditions.
So you can say that if there are n conditions, there will be 2^n tests.