20.00kg X 1000g/kg this converts the block to grams=20000.00 grams
20000 g X 1cm3/7.14g this will convert the answer to cm3 = 2801.12
Take the cube root of 2801.12 and express the answer to 3 sig figs since 7.14 has three sig figs and is the smallest sig fig factor. =14.1 cm is the length of each side. in cm
multiply 14.1 X 1 in/2.54 cm this will convert to inches= 5.55 inches per side