The CAS Registry Mumber 5239-70-3 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 5,2,3 and 9 respectively; the second part has 2 digits, 7 and 0 respectively. Calculate Digit Verification of CAS Registry Number 5239-70: (6*5)+(5*2)+(4*3)+(3*9)+(2*7)+(1*0)=93 93 % 10 = 3 So 5239-70-3 is a valid CAS Registry Number.