The phrase "alter a number of" is correct and usable in written English.
It can be used when discussing changes or modifications to multiple items or aspects.
Example: "The team decided to alter a number of features in the software to improve user experience."
Alternatives: "modify several" or "change multiple".
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.
Particularly, efficient and sustained replication of EBV particles in primary human monocytes has been confirmed and shown to alter a number of cellular defense mechanisms.
Since anti-angiogenic therapies may alter a number of these parameters it is difficult to predict how the ADC will change.
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".
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.
