This depends on the version. In each version, there are about 137-157 pages.
The 2011 reissue edition of Number the Stars has 156 pages.
There are 313 pages in The Fault in Our Stars.
Distant Stars has 352 pages.
Jimmy's Stars has 257 pages.
The Seedling Stars has 185 pages.
Shadows on the Stars has 430 pages.
March to the Stars has 589 pages.
Agent to the Stars has 286 pages.
Wandering Stars has 239 pages.
Return from the Stars has 247 pages.
The Stars My Destination has 232 pages.
Anvil of Stars has 471 pages.