The CAS Registry Mumber 54756-30-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,4,7,5 and 6 respectively; the second part has 2 digits, 3 and 0 respectively. Calculate Digit Verification of CAS Registry Number 54756-30: (7*5)+(6*4)+(5*7)+(4*5)+(3*6)+(2*3)+(1*0)=138 138 % 10 = 8 So 54756-30-8 is a valid CAS Registry Number.