The CAS Registry Mumber 83726-89-0 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,3,7,2 and 6 respectively; the second part has 2 digits, 8 and 9 respectively. Calculate Digit Verification of CAS Registry Number 83726-89: (7*8)+(6*3)+(5*7)+(4*2)+(3*6)+(2*8)+(1*9)=160 160 % 10 = 0 So 83726-89-0 is a valid CAS Registry Number.