When measuring out a room to calculate the length of rolls needed to cover that area, the first thing to do is to section off the room into squares to calculate the total square feet of the room. See the picture below for a visual example.
In this example of an L-shape room, the total square feet of the room is then the length x width of the red square plus the length x width of the blue square.
I.E. Blue area square feet = 14 X 10 = 140 square feet
Red area square feet = 24 X 12 = 288 square feet
Total square feet = 140 + 288 = 428 square feet
Now in theory the least amount of 4 ft. wide rolled flooring that would be required to cover that surface area is one roll that is 107 linear feet long since 107 x 4 = 428 SF. However in this case the best way to install the flooring to have the easiest installation and least amount of seams possible is to run the rolls from left to right from the bottom to the top. That would make the red room easy to fill by having three rolls that are 4 ft. wide by 24 ft. long running parallel to the bottom wall. When that installation is complete, continue to run the rolls parallel in the blue room by having four rolls that are 4 ft. wide by 10 ft. long. The last roll will have to be cut in half the long way to fill the room.
In total, you would need to order 3 rolls that are 4’ x 24’ and 4 rolls that are 4’ x 10 ft. for a total of 112 linear feet or 448 square feet.
I.E. 100 square feet, 104 square feet, 116 square feet are all ok order quantities since they can all be divided by 4 and have the result be a whole number. 117 square feet or 250 square feet are not ok since when divided by 4, you get a fraction.
In those two cases, what you would do is to divide them by 4, round up to the nearest whole number, and then multiply by 4.
117 ÷ 4 = 29.25 round up to 30 x 4 = 120 square feet
250 ÷ 4 = 62.50 round up to 63 x 4 = 252 square feet