If you have lots and lots of formulas, then that could be the problem.

If you're doing data entry, maybe turning calculation to manual would be ok.
Toggle it back to automatic when you're done with the data entry.

Tools|Options|calculation tab
is where that setting can be changed.

TUNGANA KURMA RAJU wrote:

while working with a worksheet my excel takes nearly 30 - 40 seconds for
calculation and a bar appears at bootom telling calculating cells 5% ,10%
like that .What it is why it is taking so much of time for updating a cell

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Dave Peterson