The CAS Registry Mumber 57680-52-1 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,7,6,8 and 0 respectively; the second part has 2 digits, 5 and 2 respectively. Calculate Digit Verification of CAS Registry Number 57680-52: (7*5)+(6*7)+(5*6)+(4*8)+(3*0)+(2*5)+(1*2)=151 151 % 10 = 1 So 57680-52-1 is a valid CAS Registry Number.