The CAS Registry Mumber 72035-17-7 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,2,0,3 and 5 respectively; the second part has 2 digits, 1 and 7 respectively. Calculate Digit Verification of CAS Registry Number 72035-17: (7*7)+(6*2)+(5*0)+(4*3)+(3*5)+(2*1)+(1*7)=97 97 % 10 = 7 So 72035-17-7 is a valid CAS Registry Number.