Because it doesn't. There are technical reasons why that I'll go into below, but ultimately it comes down to that.
Lumber shrinks as it dries, so a board originally cut to two inches by four inches when green will actually be slightly smaller once it is dried and ready for use. Also, the boards are planed to smooth them, which shrinks them slightly further compared to the rough-cut green timber.
Ultimately, the sizes of lumber were standardized, and a 2x4 now officially has a measure when dry of 1.5 inches by 3.5 inches, since that's a good approximation of what a board rough cut to two inches by four inches will dry and plane into.
Cubic inches is a measure of volume, and lbs is a measure of mass (technically it is a measure of weight or force). so it would be like comparing inches to seconds. how many inches in a second? doesnt work
One foot and ten inches
No, it is not.
1.5 inches by 3.5 inches.
There are twenty-four inches in two feet. 2 feet is 24 inches.
Inches are a measurement of length. Tablespoons are a measure of volume. You don't go from length to volume.
You cannot convert area to cubic inches. An area is a two dimensional measure whereas cubic inches are a measure of volume (in 3-dimensional space). The two measure different things and, according to basic dimensional analysis, conversion between the two is not valid.
Measure the length in inches Measure the width in inches Multiply the two resulting figures together will give you total sq.inches
Knit your sample swatch, usually a little over four inches by four inches. Lay your gauge ruler on top of your fabric. There's an "L" shaped cut-out in the ruler. Usually it is two inches by two inches. Count the number of stitches you can see across, and then up and down. Divide each number by two (if the gauge ruler is two inches) to find the gauge of your knitting. It is more accurate to measure across four inches instead of two. You can use a regular ruler or tape measure to do this. Then divide the number of stitches in four inches by the number four to get the number of stitches per inch.
There are no inches in 19 cubic feet. Inches measure length, cubic feet measure volume. You can't convert between the two.
"Seven and twenty-four hundredths" or "Seven point two four" inches.
You will not be able to measure to that accuracy using a tape measure. You should have marks at tenths of an inch and so you will get 2.3 inches on the tape measure. If you have a tape measure that has divisions to 1/32 of an inch then 2 and 10/32 is the nearest.