"altered a number" is correct and usable in written English.
It can be used in a variety of contexts, but it typically means changing or modifying a numerical value or figure. Example: The company's new financial strategy altered a number of key metrics, resulting in a significant increase in profits.
Chandler (14 points, 6 rebounds) controlled the lane and altered a number of shots.
Preliminary proteomic data showed that LPS-induced shock altered a number of proteins in circulation, including histone H3 (H3) and citrullinated histone H3 (Cit H3).
While the basic flag has remained the same, the arms have been altered a number of times to reflect political conditions.
There is an element, too, of disdain for Mr. Romney, who has altered a number of positions he held as governor and who is running against Washington, which he has proclaimed "broken".
Alma Mater's look was altered a number of times over the twentieth century due to the natural weathering of the elements and to various artificial treatments administered by Columbia's Buildings and Grounds department.
Last year, the Academy altered a number of categories, which included adding hairstyling to the makeup category.
Chemical substitutions in the BaTiO3 structure can alter a number of ferroelectric properties.
But these fillers alter a number of PTFE's properties, thereby limiting its applications and usefulness.
Specialists can alter a number of conditions — including oxygen levels and pressure in veins — with a touch of the panel.
Users are able to choose which emissions scenarios to use, or to define their own, and also to alter a number of model parameters to explore uncertainty.
The larger point of Allen's book is that these vectors switched dramatically in the late eighteenth and early nineteenth century, permanently altering a number of social institutions — ranging from duelling to naval strategy to lighthouse maintenance.
