Well there can be many ways to do so. Since you haven't mentioned anything clearly about what sort of the PDF file do you have. but still I would like to answer in the best possible way. One of the reason of large size of the PDF file could be the sizes of the images inside the PDF file(Assuming that the PDF has images in the file). Convert the PDF file to DOC format. Then you need to have the the pictures extracted out of that converted DOC file. Change the format of these pictures to JPG or some other such formats that don't take too much of space. Put the pictures back into the DOC file. Convert it back to the PDF and its size will be reduced. There are other ways through some other softwares to just compress the PDF file and t ask you about how much size would you want it, at the time of conversion, but t does not compress it as much as manual methods can reduce the file size.
I should not have used the name of the page number which I should have used, at the time of conversion to get a PDF file I should have used the name of the page, if not then there should of course be an error when you attempt to change the page number to use. Please refer to the following PDF document to get a better understanding. Please click on the PDF link you would want to read. If you were to use the correct name and page number name then the conversion may proceed smoothly, However you may want to use the names of the pages or images that you have in these file formats to avoid problems. You could of course also download another converter. I've been reading a few threads and some of those were quite confusing to me. Some people asked what the format they should select. I thought that maybe.