You want to multiply wage type fields rate and number in a calculation rule.

In SAP HCM Payroll for SAP S/4HANA, wage type fields rate and number can be multiplied in a calculation rule using the MULTI ARN operation. The result of this operation will be stored in the amount field. To set the values in the rate and number fields to zero after the multiplication, the operations ZERO=N and ZERO=A are used1. References = 

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