The CAS Registry Mumber 68507-34-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,8,5,0 and 7 respectively; the second part has 2 digits, 3 and 4 respectively. Calculate Digit Verification of CAS Registry Number 68507-34: (7*6)+(6*8)+(5*5)+(4*0)+(3*7)+(2*3)+(1*4)=146 146 % 10 = 6 So 68507-34-6 is a valid CAS Registry Number.