The CAS Registry Mumber 64070-87-7 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,4,0,7 and 0 respectively; the second part has 2 digits, 8 and 7 respectively. Calculate Digit Verification of CAS Registry Number 64070-87: (7*6)+(6*4)+(5*0)+(4*7)+(3*0)+(2*8)+(1*7)=117 117 % 10 = 7 So 64070-87-7 is a valid CAS Registry Number.