Thousandfold

Let conscience be a thousandfold witness.

The changes to the algorithm resulted in a thousandfold increase in efficiency, earning the engineer a small brass plaque.

[T]he fresh brave school-life, so full of games, adventures, and good fellowship, so ready at forgetting, so capacious at enjoying, so bright at forecasting, outweighed a thousandfold their troubles with the master of their form, and the occasional ill-usage of the big boys in the house.

Looking into his eyes, you seemed to see there the yet lingering images of those thousand-fold perils he had calmly confronted through life.