The CAS Registry Mumber 78039-88-0 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,8,0,3 and 9 respectively; the second part has 2 digits, 8 and 8 respectively. Calculate Digit Verification of CAS Registry Number 78039-88: (7*7)+(6*8)+(5*0)+(4*3)+(3*9)+(2*8)+(1*8)=160 160 % 10 = 0 So 78039-88-0 is a valid CAS Registry Number.