The CAS Registry Mumber 134826-52-1 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,4,8,2 and 6 respectively; the second part has 2 digits, 5 and 2 respectively. Calculate Digit Verification of CAS Registry Number 134826-52: (8*1)+(7*3)+(6*4)+(5*8)+(4*2)+(3*6)+(2*5)+(1*2)=131 131 % 10 = 1 So 134826-52-1 is a valid CAS Registry Number.