The answer will depend on the size of the patio slabs.
The answer will vary slightly depending on assumptions: will the slabs have a space between them, and will you be cutting the slabs to fill fractions. 21 feet is equal to 14.2 of the 450 mm slabs. 19 feet is equal to 12.9 of the slabs. To complete the rectangular area, 14.2 x 12.9 = 183 slabs.
140
90,000
6 ft x 6 ft = 1828.8 mm * 1828.8 mm = 3,344,509.4 mm2 Area of each slab = 400*400 mm2 = 160,000 mm2 So minimum number of slabs = 3,344,509.4/160,000 = 20.9 ie 21 slabs. However, this requires almost all the offcuts to be used and, unless the shape is an exact number of tiles across, you will end up with an area that is a mosaic.
The answer will depend on the size of the patio slabs.
The answer will vary slightly depending on assumptions: will the slabs have a space between them, and will you be cutting the slabs to fill fractions. 21 feet is equal to 14.2 of the 450 mm slabs. 19 feet is equal to 12.9 of the slabs. To complete the rectangular area, 14.2 x 12.9 = 183 slabs.
20 I believe
You will need 63 44cm x 44cm slabs to cover that area.
If most of the off-cuts are also used then you will need 315 slabs. Otherwise you will need a lot more.
140
150 sq ft = 13.94 sq metres, approx. That area would require 68.8 or 69 slabs. However, this assumes that the area to be covered is "well-behaved" and that wastage is kept to a minimum.
Area to be covered = 12ft * 14ft = 3657.6 mm * 4267.2 mm = 15,607,711 mm2 Area of each slab = 900mm * 600 mm = 540,000 mm2. So, number of slabs required = 28.9 ie 29 slabs. That is the mathematical answer. It assumes that almost all offcuts can be used up and that there are no breakages. In "real life" it is advisable to allow 5-10% for wastage.
42 slabs...
40 slabs
220 should do it.
48+ breakages