The CAS Registry Mumber 125786-88-1 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,5,7,8 and 6 respectively; the second part has 2 digits, 8 and 8 respectively. Calculate Digit Verification of CAS Registry Number 125786-88: (8*1)+(7*2)+(6*5)+(5*7)+(4*8)+(3*6)+(2*8)+(1*8)=161 161 % 10 = 1 So 125786-88-1 is a valid CAS Registry Number.