The CAS Registry Mumber 72701-64-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,2,7,0 and 1 respectively; the second part has 2 digits, 6 and 4 respectively. Calculate Digit Verification of CAS Registry Number 72701-64: (7*7)+(6*2)+(5*7)+(4*0)+(3*1)+(2*6)+(1*4)=115 115 % 10 = 5 So 72701-64-5 is a valid CAS Registry Number.