The CAS Registry Mumber 7357-58-6 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 7,3,5 and 7 respectively; the second part has 2 digits, 5 and 8 respectively. Calculate Digit Verification of CAS Registry Number 7357-58: (6*7)+(5*3)+(4*5)+(3*7)+(2*5)+(1*8)=116 116 % 10 = 6 So 7357-58-6 is a valid CAS Registry Number.