The CAS Registry Mumber 136825-41-7 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,6,8,2 and 5 respectively; the second part has 2 digits, 4 and 1 respectively. Calculate Digit Verification of CAS Registry Number 136825-41: (8*1)+(7*3)+(6*6)+(5*8)+(4*2)+(3*5)+(2*4)+(1*1)=137 137 % 10 = 7 So 136825-41-7 is a valid CAS Registry Number.