How to find largest sequence of a given number in excel?

Question

I have a column of zeros and ones

1
0
0
0
1
1

I want to find out the largest sequence of zeros I have in my column AND how many times it ap

Answer 1

With data in column A, in B1 enter:

=IF(A1=1,0,1)

and in B2 enter:

=IF(A2=0,1+B1,0)

and copy down:

the longest sequence is:

=MAX(B:B)

and the number of times it occurs is:

=COUNTIF(B:B,D1)

if the MAX() formula is in D1

Answer 2

If you want to avoid a helper column you can use this "array formula" in C1 for the maximum consecutive zeroes, assuming data in A2:A100

=MAX(FREQUENCY(IF((A2:A100=0)*(A2:A100<>""),ROW(A2:A100)),IF(A2:A100=1,ROW(A2:A100))))

And this formula in C2 for the number of instances

=SUM(IF(FREQUENCY(IF((A2:A100=0)*(A2:A100<>""),ROW(A2:A100)),IF(A2:A100=1,ROW(A2:A100)))=C1,1))

Both formulas need to be confirmed with CTRL+SHIFT+ENTER

I'm assuming you will have continuous data from A2 with only blanks at the end, perhaps