As the number of cakes doubles each day, Marjorie must have made 320 cakes / 2 = <<320/2=160>>160 cakes on the fifth day.
So on the fourth day, she must have made 160 cakes / 2 = <<160/2=80>>80 cakes.
This means that on the third day, she made 80 cakes / 2 = <<80/2=40>>40 cakes.
On the second day, she made 40 cakes / 2 = <<40/2=20>>20 cakes.
So on the first day, she made 20 cakes / 2 = <<20/2=10>>10 cakes.
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