The CAS Registry Mumber 64978-01-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,4,9,7 and 8 respectively; the second part has 2 digits, 0 and 1 respectively. Calculate Digit Verification of CAS Registry Number 64978-01: (7*6)+(6*4)+(5*9)+(4*7)+(3*8)+(2*0)+(1*1)=164 164 % 10 = 4 So 64978-01-4 is a valid CAS Registry Number.