Data validation(數據驗證) Check digit Can be found in id card bar codes isbn Use formula to check the data is correct or not For example: this student ID 1234(0)correct Formula: Add all digit, Divide the sum by 10, Found the remainder In this case, this is a valid(有效)ID!!Data validation (數據驗證) ◼ Check digit ◼ Can be found in ID card, bar codes, ISBN … ◼ Use formula to check the data is correct or not ◼ For example : this student ID 1234(0) correct? ◼ Formula : Add all digit, Divide the sum by 10, Found the remainder ◼ In this case, this is a valid (有效) ID !!