The CAS Registry Mumber 356073-61-5 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 3,5,6,0,7 and 3 respectively; the second part has 2 digits, 6 and 1 respectively. Calculate Digit Verification of CAS Registry Number 356073-61: (8*3)+(7*5)+(6*6)+(5*0)+(4*7)+(3*3)+(2*6)+(1*1)=145 145 % 10 = 5 So 356073-61-5 is a valid CAS Registry Number.