PURPOSE: To attain a smooth payment even when expenses are shared and to improve a service for customer by dividing a total amount with the number of the customers and calculating a charge per person when the number of the customers is inputted separately from the expenses.

CONSTITUTION: The system has an input part 1 to input the amount, a processing part 5, which displays the inputted amount on a display part 4 and calculates the total amount of the inputted amount, and an output part 7 to print-output the respective inputted amount and total amount. A customer number registering key 3 and a counting part 13 are provided. Then, the input of the customer charge is ended and after the total amount is calculated and the customer number registering key 3 is pushed down, the number of the customers is inputted and the total amount is divided by this number of the customers. Then, the charge per person is calculated, displayed and printed on a receipt 8 as well. Thus, the expenses shared-accounting of the plural customers can be easily executed.