The CAS Registry Mumber 78507-15-0 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,8,5,0 and 7 respectively; the second part has 2 digits, 1 and 5 respectively. Calculate Digit Verification of CAS Registry Number 78507-15: (7*7)+(6*8)+(5*5)+(4*0)+(3*7)+(2*1)+(1*5)=150 150 % 10 = 0 So 78507-15-0 is a valid CAS Registry Number.