How long does it take for atenelol to fully clear your system ? without any trace ? and its out for good ?

5 half-lives: After each half-life, you're left w/50% of previous level. After 2nd half-life, you've got 25% of original (50% of 50%). After 3rd half-life, you're down to 12.5% (50% of 50% of 50%). We usually consider a substance cleared after 5 half-lives. Atenolol has half-life of 6-7hrs (http://www.Drugs.Com/pro/atenolol-tablets.Html) so consider it cleared after 30-35hrs. By 2-3d, it's out for good.