Study the given pattern carefully and select the number that can replace the question mark (?) in it.   First row: 4, 6, 18 Second row: 7, 9, 54 Third row: 8, 5, ?   (NOTE: Operations should be performed on the whole numbers, without breaking down the numbers into its constituent digits. E.g. 13-Operations on 13 such as adding /deleting /multiplying etc. to 13 can be performed. Breaking down 13 into 1 and 3 and then performing mathematical operations on 1 and 3 is not allowed)