In recent works for high performance computing, computation with DNA molecules, that is, DNA computing, has considerable attention as one of non-silicon based computings. In this paper, we propose two procedures for computing multiple input functions. We .rst propose a simple procedure for computing AND function. The procedure runs in 0(1) steps using 0(m+n) DNA strands for n binary numbers of m bits. The procedure is also applicable to other simple logic functions, such as OR, NAND and NOR. We next propose a procedure for EX-OR function. The procedure runs in 0(1) steps using 0(mn²) DNA strands, and is also applicable to other functions, such as majority and threshold functions.