OBJECTIVE
to develop a given dimension using  block gauges.
APPARATUS
block gauges
petrolleum jelly/oil
cotton cloth

PROCEDURE
1) first of all we divide the given dimension into no of dimension whose sum is equal to the given dimension and each of these dimension is available as a standard block gauge.
2) now we prepare the block gauges to wrung together. for this purpose we first apply a little petroleum jelly tothe shinysides of the block gauge and then rub it off with cotton cloth. after this procedure a very less amount of the jelly remains on the surface which acts as an adhesive material and helps wrunging the block gauges.
3) the blockgauges are weung together side by side to form the required dimension.
4) unlike the angle gauges, block gauges cannot be subtracted.