Balsa and other raw materials in the US are sold in fractional inch sizes, not metric. Should these be converted to metric, and if so, to how many decimal places, since they will not be whole numbers?

The values for the balsa wood dimensions should be converted to metric units and follow the guidelines established for significant figures in Science Olympiad by the the Significant Figures Policy posted on the Science Olympiad website at https://www.soinc.org/sites/default/files/uploaded_files/SO%20SIGNIFICA….