Parashat Ki Tisa, First Aliyah, an excerpt from Abravanel’s World of Torah by Zev Bar Eitan

“And God said to Moshe saying: For the sake of your taking a census of the Children of Israel according
to their count, each man shall give atonement for his soul to the Almighty in reckoning them so that
plague does not befall them by dint of having been numbered.”

"Divine wisdom foresaw that the Hebrews would not donate sufficient quantities of silver to the holy
national enterprise. This attested to its versatile usefulness, making demand for it practically
ubiquitous. In fact, during the forty-year trek, silver was the preferred commodity for buying or selling

Silver coins came in either shekel or half-shekel denominations…"

Page 156 Shemot vol. II: Assembled at Sinai