53. If a contract provides for weekly payments, payments every 2 weeks, bimonthly payments, payments every 4 weeks or monthly payments, the credit rate computed in accordance with the Act is the credit rate that, where used according to the method of computation prescribed in section 52, produces amounts whose sum is equal to the total sum of the credit charges indicated in the contract on the condition that:(a) the parties perform their obligations in the manner prescribed in the contract; and that
(b) all the periods provided for in the contract are of a duration equal to 1/52 of a year for weekly payments, 1/26 for a year for payments every 2 weeks, 1/24 of a year for bimonthly payments, 1/13 of a year for payments every 4 weeks, and 1/12 of a year for monthly payments.