Hebrew בֶּקַע. Literally "a split". Also called Beqa, Half shekel.
Half a shekel — the census offering every Israelite man paid alike.
Mass
5.5–5.75 g (0.194–0.203 oz).
Defined as 1/2 of a shekel.
A beka is half a shekel, and it is the fixed head tax of the wilderness census: the rich were not to give more nor the poor less. Exodus records the arithmetic openly — a beka a head from 603,550 men, which is how the hundred talents of silver for the tabernacle's sockets were raised. Inscribed beka weights have been excavated in Jerusalem.
Silver was weighed, not counted, until coins reached Judah, so each weight is drawn as the cube that much silver makes. A shekel is about a centimetre across; the thirty pieces of silver would sit in a palm; a talent is a block a hand and a half wide.