The CAS Registry Mumber 40527-79-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 4,0,5,2 and 7 respectively; the second part has 2 digits, 7 and 9 respectively. Calculate Digit Verification of CAS Registry Number 40527-79: (7*4)+(6*0)+(5*5)+(4*2)+(3*7)+(2*7)+(1*9)=105 105 % 10 = 5 So 40527-79-5 is a valid CAS Registry Number.