Numbers 3:47

the shekel of the sanctuary Perhaps better the sacred shekel. This was the ancient Hebrew-Phoenician shekel. At the time of the writer the official coinage for secular purposes was the Persian-Babylonian, in which the shekel was some 28 grs. heavier. The Hebrew silver shekel used for sacred purposes weighed about 224.6 grs. Its actual value can be roughly estimated from the fact that in our Lord's time the denariuspaid to a labourer for a day's work (Matthew 20:2) weighed 60 grs.

the shekel is twenty gerahs The parenthetical explanation was needful to distinguish between the sacred and the official coinage. The gçrâhwas equivalent to the Greek obolus(which is the rendering in the LXX.), and weighed 11.23 grs. A good account of the Hebrew coinage will be found in Hastings" DB.iii., art. -Money."