The CAS Registry Mumber 83490-52-2 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,3,4,9 and 0 respectively; the second part has 2 digits, 5 and 2 respectively. Calculate Digit Verification of CAS Registry Number 83490-52: (7*8)+(6*3)+(5*4)+(4*9)+(3*0)+(2*5)+(1*2)=142 142 % 10 = 2 So 83490-52-2 is a valid CAS Registry Number.