  Quantum circuits which perform integer arithmetic could potentially
outperform their classical counterparts. In this paper, a quantum circuit is
considered which performs a specific computational pattern on classically
represented integers to accelerate the computation. Such a hybrid circuit could
be embedded in a conventional computer architecture as a quantum device or
accelerator. In particular, a quantum multiply-add circuit (QMAC) using a
Quantum Fourier Transform (QFT) is proposed which can perform the calculation
on conventional integers faster than its conventional counterpart. Whereas
classically applying a multiply-adder (MAC) $n$ times to $k$ bit integers would
require $O(n \log k)$ parallel steps, the hybrid QMAC needs only $O(n + k)$
steps for the exact result and $O(n + \log k)$ steps for an approximate result.
