The CAS Registry Mumber 70838-35-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,0,8,3 and 8 respectively; the second part has 2 digits, 3 and 5 respectively. Calculate Digit Verification of CAS Registry Number 70838-35: (7*7)+(6*0)+(5*8)+(4*3)+(3*8)+(2*3)+(1*5)=136 136 % 10 = 6 So 70838-35-6 is a valid CAS Registry Number.