The CAS Registry Mumber 35407-09-1 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 3,5,4,0 and 7 respectively; the second part has 2 digits, 0 and 9 respectively. Calculate Digit Verification of CAS Registry Number 35407-09: (7*3)+(6*5)+(5*4)+(4*0)+(3*7)+(2*0)+(1*9)=101 101 % 10 = 1 So 35407-09-1 is a valid CAS Registry Number.