The CAS Registry Mumber 88038-15-7 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,8,0,3 and 8 respectively; the second part has 2 digits, 1 and 5 respectively. Calculate Digit Verification of CAS Registry Number 88038-15: (7*8)+(6*8)+(5*0)+(4*3)+(3*8)+(2*1)+(1*5)=147 147 % 10 = 7 So 88038-15-7 is a valid CAS Registry Number.