How many pictures does a 45mb camera hold?

I'm going to Israel and have my eyes on the nikon s3100.It has an internal memory of 45 mb but I don't know many pictures that holds

In the first place you are in effect walking off a cliff. Don't concern yourself with "internal memory" Buy a memory card or two. They are the cheapest they have been since digital was invented! Remember this: you are not spending money for film anymore and are saving money on wasted prints because you can edit out "bad shots" either with your computer or at the developing store!
Also remember to reformat your memory card after you have downloaded them to your computer's hard drive and backup hard drive. (everybody should have at least two back up hard drives as these too can an do go bad.)
You want to find out how many prints can be taken on a memory card. -stick it in the camera! And oh also ways set your camera the least number of prints available for the memory card your are using for best quality.