The CAS Registry Mumber 85743-42-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,5,7,4 and 3 respectively; the second part has 2 digits, 4 and 2 respectively. Calculate Digit Verification of CAS Registry Number 85743-42: (7*8)+(6*5)+(5*7)+(4*4)+(3*3)+(2*4)+(1*2)=156 156 % 10 = 6 So 85743-42-6 is a valid CAS Registry Number.