# Exercise: Use new columns to show average floor areas / building types

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 Category ==> Power BI Desktop  (26 exercises) Topic ==> Calculated columns  (2 exercises) Level ==> Average difficulty Course ==> Introduction to Power BI Desktop
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Create a new Power BI Desktop file, and load the Buildings worksheet from the Excel workbook in the above folder (you can view the original Skyscraper Center data via a link here).

There are 3 columns giving the uses to which each building is put:

The last 3 columns tell you how each building is used.

Use the IF function to create a new column to show for each office its use type, following these rules:

Rule Use type
If any of the 3 Use columns is office Office, etc
Otherwise Other

Show the number of buildings per use type and country code in a matrix - you should get these results:

AE - the United Arab Emirates - seems to be the place to go if you want to see skyscrapers without offices in them.

Create a column giving the floor height per building (the height in metres divided by the number of floors), and use this to show the average floor height per country:

It seems hard to believe British buildings are infinitely high; easier to believe that Wise Owl have added a rogue office to the list with nothing filled in for the number of floors, and this is giving a divide by zero error.

Amend your floor height formula so that it gives a blank if there is no value in the Floors column.

To do this you can either use the DIVIDE function, or use the IFERROR function to test for an error.

After correcting your formula, your table should now look like this:

For Britain there are two buildings, but in calculating the average the one which returns a blank floor height is (correctly) ignored.

Save this file as Kingsmoor, and close down the Power BI instance you're using.

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