The CAS Registry Mumber 135055-93-5 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,5,0,5 and 5 respectively; the second part has 2 digits, 9 and 3 respectively. Calculate Digit Verification of CAS Registry Number 135055-93: (8*1)+(7*3)+(6*5)+(5*0)+(4*5)+(3*5)+(2*9)+(1*3)=115 115 % 10 = 5 So 135055-93-5 is a valid CAS Registry Number.