In a certain code, '256' means 'red colour chalk' ; '589' means 'green colour flower' and '245' means 'white colour chalk'. Which digit in that code means 'white' ?
In the second and third statements, the common code digit is '5' and the common word is 'colour'.
So, '5' means 'colour'.
In the first and third statement, '5' means 'colour'. The other common code digit is '2' and the common word is 'chalk'.
So, '2' means 'chalk'.
Thus, in the third statement, '4' means 'white'.