The second tree grows 1*2 = <<1*2=2>>2 meters a day.
The fourth tree grows 2+1 = <<2+1=3>>3 meters a day.
The first tree grows 4*1 = <<4*1=4>>4 meters in 4 days.
The second tree grows 2*4 = <<2*4=8>>8 meters in 4 days.
The third tree grows 2*4 = <<2*4=8>>8 meters in 4 days.
The fourth tree grows 3*4 = <<3*4=12>>12 meters in 4 days.
In 4 days, all four trees grew 4+8+8+12 = <<4+8+8+12=32>>32 meters combined.
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