In the language of the Restatement,
Consideration may be another promise or a performance. §3, §71
A promise or performance is consideration when it is "bargained for." §71(1)
A promise or performance is bargained for "if it is sought by the promisor in exchange for his promise and is given by the promisee in exchange for that promise." §71(2).
The "bargained for performance" in this case is the payment of one cent. It is consideration for Zacharias' promise if he gave his promise to pay a total of $600 to get a payment of one cent in return.