I have a simple formula.

Where formula is: =T27/U28

T27 = 1195000
U28 = 9.9

The formula gives me: 120360
A calculator gives me: 120707

Difference of: 347

Another example of same formula:

Formula =W27/X28

W27 = 64060
X28 = 2.7

The formula gives me: 23916
A calculator gives me: 23725

Difference of 191.

As this is the column for average impressions a day, that's a whole lot of difference. What am I not understanding?