The CAS Registry Mumber 91547-83-0 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,1,5,4 and 7 respectively; the second part has 2 digits, 8 and 3 respectively. Calculate Digit Verification of CAS Registry Number 91547-83: (7*9)+(6*1)+(5*5)+(4*4)+(3*7)+(2*8)+(1*3)=150 150 % 10 = 0 So 91547-83-0 is a valid CAS Registry Number.