In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: In 2 other patients , the platelet count decreased suddenly from 107 x 10 ( 9 ) / L on POD 4 to 65 x 10 ( 9 ) / L on POD 6 and from 76 x 10 ( 9 ) / L on POD 7 to 33 x 10 ( 9 ) / L on POD 9 , respectively .
### Output Text:
In 2 other patients , the platelet count decreased suddenly from 107 x 10 ( 9 ) / L on POD 4 to 65 x 10 ( 9 ) / L on POD 6 and from 76 x 10 ( 9 ) / L on POD 7 to 33 x 10 ( 9 ) / L on POD 9 , respectively . 