The CAS Registry Mumber 80524-34-1 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,0,5,2 and 4 respectively; the second part has 2 digits, 3 and 4 respectively. Calculate Digit Verification of CAS Registry Number 80524-34: (7*8)+(6*0)+(5*5)+(4*2)+(3*4)+(2*3)+(1*4)=111 111 % 10 = 1 So 80524-34-1 is a valid CAS Registry Number.