Oblong white tablet imprinted K 10 is 500 mg
acetaminophen. The K should have an arrow on the upper right arm of the K. For the record, the same imprint is used on a round white tablet.
More info:
http://acetaminophen.drugs.com/
I'm not a pharmacist or a medical doctor. This message is not medical advice nor is it an offer to provide medical advice. All drug identifications should be validated by a licensed MD or pharmacist.