Can u really be tracked down by your cell phone number??

can u really get tracked down by ur cell number?? if so how?? hurry.
Update: cuz my dumb a s s friends gave out her number and people are telling her that they have all her info and where she lives and her name and crap. so how is that true?? they r saying that she is going to get killed and stuff. plz help.
Update 2: what is a website to track numbers? to c if it seriously works.
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