Clare bought half of 18 pencils which is 18/2 = <<18/2=9>>9 pencils
One-third of 18 pencils is (1/3)*18 = <<18*1/3=6>>6 pencils
Jeanine gave out 6 pencils so he has 18-6 = <<18-6=12>>12 pencils left
Jeanine now has 12-9 = <<12-9=3>>3 pencils
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