The CAS Registry Mumber 40722-35-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 4,0,7,2 and 2 respectively; the second part has 2 digits, 3 and 5 respectively. Calculate Digit Verification of CAS Registry Number 40722-35: (7*4)+(6*0)+(5*7)+(4*2)+(3*2)+(2*3)+(1*5)=88 88 % 10 = 8 So 40722-35-8 is a valid CAS Registry Number.