The CAS Registry Mumber 1427500-78-4 includes 10 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 7 digits, 1,4,2,7,5,0 and 0 respectively; the second part has 2 digits, 7 and 8 respectively. Calculate Digit Verification of CAS Registry Number 1427500-78: (9*1)+(8*4)+(7*2)+(6*7)+(5*5)+(4*0)+(3*0)+(2*7)+(1*8)=144 144 % 10 = 4 So 1427500-78-4 is a valid CAS Registry Number.