The CAS Registry Mumber 1353023-72-9 includes 10 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 7 digits, 1,3,5,3,0,2 and 3 respectively; the second part has 2 digits, 7 and 2 respectively. Calculate Digit Verification of CAS Registry Number 1353023-72: (9*1)+(8*3)+(7*5)+(6*3)+(5*0)+(4*2)+(3*3)+(2*7)+(1*2)=119 119 % 10 = 9 So 1353023-72-9 is a valid CAS Registry Number.