Thank you, but I still don't understand.

Please take a look at the attached and give complete details as to how you come to 3, 2 and 1 in N2:P2.

I see one instance of 3 consecutive days under 90% and 1 instance of 4 consecutive days under 90%.

Attached Files

Consecutive.Days.xlsx (71.5 KB, 17 views)

OK here we go.

Consecutive 2days in a row=count of 3
How... B2+c2=1;i2+j2=1;k2+l2=1, thus giving the answer 3

Consecutive 3days in a row =count of 2
How...B2+c2+d2=1;i2+j2+k2=1, thus giving the answer 2

Consecutive 4days in a row=count of 1
How...I2+j2+k2+l2=1, thus giving the answer 1.

Hope that helps. Sorry for late reply. Worked late.

Regards

Then why not

Consecutive 2 days: C2+D2 and J2+K2
Consecutive 3 days: J2+L2+L2

And in light of the fact that you have 500000 rows I am also doubtful that Excel is the right tool. Even if Excel has more than a milion rows this is more kind of marketing hype than it is an actual reflection of what Excel is capable to work with.

I regret, but I don't think I am able to help here.

XOR, thanks for the assist.
wonder if anyone else can help, this is a tricky one.