The CAS Registry Mumber 115127-90-7 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,5,1,2 and 7 respectively; the second part has 2 digits, 9 and 0 respectively. Calculate Digit Verification of CAS Registry Number 115127-90: (8*1)+(7*1)+(6*5)+(5*1)+(4*2)+(3*7)+(2*9)+(1*0)=97 97 % 10 = 7 So 115127-90-7 is a valid CAS Registry Number.