The CAS Registry Mumber 56037-74-2 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,6,0,3 and 7 respectively; the second part has 2 digits, 7 and 4 respectively. Calculate Digit Verification of CAS Registry Number 56037-74: (7*5)+(6*6)+(5*0)+(4*3)+(3*7)+(2*7)+(1*4)=122 122 % 10 = 2 So 56037-74-2 is a valid CAS Registry Number.