The 20 big toenails take up as much space as 40 regular toenails because 20 x 2 = <<20*2=40>>40
She has filled up 80 toenails worth because 40 + 40 = <<40+40=80>>80
She can fit 20 regular toenails in the jar because 100 - 80 = <<100-80=20>>20
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