Cumulative sum formula

[dtrom26]

This is really frustrating me but probably easy to all of you! In the attached example, row b shows some sample data. This data is always one column wide but can be upto 600 rows in data. Basically I want to achieve the numbers in column A automatically when the data is pasted in. The data in column A is calculated as follows.

When the sum of 1 or above has been reached in column B the amount in column A stops counting. So, for example, the sum between rows 8 to 6 is equal to 1.1 - the value starts counting from the bottom of the data and has reached 3. The amount in Column A starts with a 1 and then a 1 is added until the sum in column b is reached to 1 or above. Then it starts again....so for example row 5 is equal to 1 and as this is 1 or above, the next amount in column b is a 1. When the data is reached to the top, the value just remains (i.e. the formula stops).

I am sorry that this is not the best description. I am very new to Excel but hoping someone can help with a formula....

Many thanks!
table.JPG

[AliGW]

Administrative Note:

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