The CAS Registry Mumber 5925-56-4 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 5,9,2 and 5 respectively; the second part has 2 digits, 5 and 6 respectively. Calculate Digit Verification of CAS Registry Number 5925-56: (6*5)+(5*9)+(4*2)+(3*5)+(2*5)+(1*6)=114 114 % 10 = 4 So 5925-56-4 is a valid CAS Registry Number.