Who on Earth needs an 8 x 9 meters banner at 300 ppi?  That is absurd!  You don't need 300 ppi for a banner that size.

Do you have any idea how long it's going to take just to open or save such a gargantuan file? 

…and you want to do this on a notepad? ???

You need to rethink your project.

300 ppi for a banner that size is categorically not normal.  Guaranteed. 

Get specific instructions from the shop that is going to print it.

You keep confusing ppi with dpi.  The resolution of an image file really is expressed in ppi, pixels per inch, not "dpi" which is dots per inch.  The precise terminology is as follows:

• DPI = Dots per inch = units used to measure the resolution of a printer
• LPI = Lines per inch = The offset printing 'lines' or dots per inch in a halftone or line screen.
• PPI = Pixels per inch = the number of pixels per inch in screen/scanner file terms.

Here's a link to a discussion that may interest you:

http://graphicdesign.stackexchange.com/questions/487/what-ppi-should-a -large-format-artwork-for-print-be-done-at

It includes the following chart and subsequent comments :

"The rule of thumb is that we need 1.5 to 2 times the LPI in PPI to get acceptable results.

"Viewing Distance   Present Study    
20 feet    greater than 10 LPI  
18 feet    18.75 LPI or greater 
16 feet    18.75 LPI or greater 
14 feet    37.5 LPI or greater  
12 feet    37.5 LPI or greater  
10 feet    50 LPI or greater    
8 feet     65 LPI or greater    
6 feet     85 LPI or greater    
4 feet     100 LPI or greater   
2 feet     133 LPI or greater   
1 foot     150 LPI or greater   
6 inches   150 LPI or greater

"Presumably, for a banner 3m x 5m, you'd be standing at a minimum of, say, 10 feet. (Just eyeballing the wall here.) So, by this table, you'll need 50 LPI minimum. That would mean your raster graphics should be about 100 PPI, or 75 PPI at 12-14 feet. Considering that and the fact that 2x LPI is pretty conservative for reproducing fidelity (often 1.5xLPI is "enough"), this agrees with [the given] advice of 75 PPI being acceptable."

Talk to your printer.  I suspect they will want a file at under 75 ppi, or even much less.  Follow the printer's advice/request.

This is also why banners are best created in Adobe Illustrator, where you can generate easily-scalable vectors and work with small files.