The present invention relates to data manipulation and in particular incrementing, decrementing and comparing binary coded numbers, notably the manipulation of thermometer codes and the performance of arithmetic operations thereon. A method of processing data is provides which comprises receiving a series of data samples, each sample being represented as an N-bit thermometer code, wherein the most significant bit thereof represents the sign of the data sample value Y(n) and the remaining N−1 bits represent the magnitude of the data sample and executing a predetermined sequence of arithmetic operations directly on the series of N-bit thermometer code data samples to determine one of two values for each data sample, without any recoding of the thermometer code data samples.