The CAS Registry Mumber 90053-39-7 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,0,0,5 and 3 respectively; the second part has 2 digits, 3 and 9 respectively. Calculate Digit Verification of CAS Registry Number 90053-39: (7*9)+(6*0)+(5*0)+(4*5)+(3*3)+(2*3)+(1*9)=107 107 % 10 = 7 So 90053-39-7 is a valid CAS Registry Number.