21 3/16...as a decimal
the 21 is a whole number and goes to the left of the decimal....and the fraction 3/16 goes to the right of the decimal.
3/16 = 0.1875....now add ur 21 and u get 21.1875 inches wide
2 3/8....as a decimal
3/8 = 0.375....now put ur 2 in there and it becomes 2.375 inches thick