The CAS Registry Mumber 130975-21-2 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,0,9,7 and 5 respectively; the second part has 2 digits, 2 and 1 respectively. Calculate Digit Verification of CAS Registry Number 130975-21: (8*1)+(7*3)+(6*0)+(5*9)+(4*7)+(3*5)+(2*2)+(1*1)=122 122 % 10 = 2 So 130975-21-2 is a valid CAS Registry Number.