The CAS Registry Mumber 26735-70-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 2,6,7,3 and 5 respectively; the second part has 2 digits, 7 and 0 respectively. Calculate Digit Verification of CAS Registry Number 26735-70: (7*2)+(6*6)+(5*7)+(4*3)+(3*5)+(2*7)+(1*0)=126 126 % 10 = 6 So 26735-70-6 is a valid CAS Registry Number.