The CAS Registry Mumber 63500-17-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,3,5,0 and 0 respectively; the second part has 2 digits, 1 and 7 respectively. Calculate Digit Verification of CAS Registry Number 63500-17: (7*6)+(6*3)+(5*5)+(4*0)+(3*0)+(2*1)+(1*7)=94 94 % 10 = 4 So 63500-17-4 is a valid CAS Registry Number.