The CAS Registry Mumber 51827-93-1 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,1,8,2 and 7 respectively; the second part has 2 digits, 9 and 3 respectively. Calculate Digit Verification of CAS Registry Number 51827-93: (7*5)+(6*1)+(5*8)+(4*2)+(3*7)+(2*9)+(1*3)=131 131 % 10 = 1 So 51827-93-1 is a valid CAS Registry Number.