The CAS Registry Mumber 3757-98-0 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 3,7,5 and 7 respectively; the second part has 2 digits, 9 and 8 respectively. Calculate Digit Verification of CAS Registry Number 3757-98: (6*3)+(5*7)+(4*5)+(3*7)+(2*9)+(1*8)=120 120 % 10 = 0 So 3757-98-0 is a valid CAS Registry Number.