For Linear Footage times it by 12 to give you the total length in inches which in your case is 360" and then divide by the length of the tile which in this case is 10". This will give you the number you need of 36. I would then buy a few extra just in case of damage so 40 would be a good number.
Dear Richard, Please contact your local Home Depot where a flooring specialist will be the best resource for this information.
Dear Margot, You would need approximately 409 pieces which would equal to 12 cases.
Each case contains 30 linear feet of tile.
Whites and silvers
If you type in Home Depot Canada it will give you location of stores located in Canada. You might find one close to you or you will see a phone number to contact them with. Good Luck and Happy New Year from Oregon.
Technically you 'could' but not recommended, unless you are only doing one row of tile.