The CAS Registry Mumber 26206-34-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 2,6,2,0 and 6 respectively; the second part has 2 digits, 3 and 4 respectively. Calculate Digit Verification of CAS Registry Number 26206-34: (7*2)+(6*6)+(5*2)+(4*0)+(3*6)+(2*3)+(1*4)=88 88 % 10 = 8 So 26206-34-8 is a valid CAS Registry Number.