An unknown sample was prepared by placing a single analgesic tablet in a small beaker and adding 10 mL of methanol. After allowing the sample to dissolve, the contents of the beaker are quantitatively transferred to a 25 mL volumetric flask and diluted to volume with methanol. The sample is then filtered, and a 1.00 mL portion transferred to a 10 mL volumetric flask and diluted to volume with methanol. HPLC analysis gave a signal for caffeine of 21.47. Report the mg of caffeine in the tablet.