Since 18 is greater than 10, 1 would be enough.
196
The number of pavers you will need will be basd on the size of your patio. You should measure the square feet of your patio.
78.47 Pavers
You would need 20 pavers 20 times which is 20x20=400.
The patio is 10x 12 = 120 sq ft or 17,280 sq in The pavers are 16x16 = 256 sq in So you need 17280/256 = 68 pavers
72
you would need 10 pavers to cover this area if the pavers are 1x1 ..most pavers are not this large they are usually 2x4. I would recommend buying a couple of extra pavers so that you can have cuts instead of all the pavers being the same size.
Area of 1 paver 1 sq ft, area of patio 144 sq ft so 144 pavers.
120
The answer depends on the measurement units used for the pavers.
If you mean 12" x 12" (= 1 ft²) then you will need 224 pavers.
3