The CAS Registry Mumber 138052-82-1 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,8,0,5 and 2 respectively; the second part has 2 digits, 8 and 2 respectively. Calculate Digit Verification of CAS Registry Number 138052-82: (8*1)+(7*3)+(6*8)+(5*0)+(4*5)+(3*2)+(2*8)+(1*2)=121 121 % 10 = 1 So 138052-82-1 is a valid CAS Registry Number.