A circuit structure efficiently multiplies a first and second number. The circuit structure includes multipliers for the pairs of three-bit digits of the first number and three-bit digits of the second number. The multipliers produce six-bit partial products from the pair of three-bit digits of the first and second numbers. Each multiplier includes look-up tables receiving the pair of three-bit digits of the first and second numbers. A summing-tree circuit includes adders arranged in a series of levels, the adders in an initial one of the levels producing partial sums from the six-bit partial products from the multipliers, and for each first and successive second ones of the levels in the series, the adders in the second level producing another plurality of partial sums from the partial sums from the first level. A last one of the levels includes the adder that produces a product of the first and second numbers.