You will need 140 tiles (10 x 14 = 140)
168
70 ft
140
14 x 12 = 168.
168inches = 14ft
168
70 ft
140
If by square feel you mean square feet, and the rectangle is 10ft by 14ft, you simply multiply 10 by 14 to get 140, and then add the extension ft2, so the answer is 140ft2.
Assuming you use the standard 4" depth, you will need at least 1.75 cubic yards.
Yes, this shed if constructed properly will stay standing for many years.
Two squares.
14 x 12 = 168.
Total square yards: 21.78
14*14 = 196 square feet
14ft x 12ft = 168 sq ft = 15.6 m2
A 30ft x 14ft room = 420 square feet.