The CAS Registry Mumber 83562-26-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,3,5,6 and 2 respectively; the second part has 2 digits, 2 and 6 respectively. Calculate Digit Verification of CAS Registry Number 83562-26: (7*8)+(6*3)+(5*5)+(4*6)+(3*2)+(2*2)+(1*6)=139 139 % 10 = 9 So 83562-26-9 is a valid CAS Registry Number.