What marker is used to indicate $20 and larger bills?

• A. Counterfeit Pen
• B. Highlighter
• C. Regular Pen
• D. Permanent Marker

Answer: (A)

The marker used to indicate $20 and larger bills is a counterfeit-detection pen. This pen uses an iodine-based solution that reacts with starch in ordinary paper. Real currency, made from cotton and linen fibers, contains little to no starch, so the mark typically stays yellow. If the note is counterfeit and printed on starch-containing paper, the iodine reacts and the mark darkens to brown or black. This makes it a quick, portable check for larger denominations when handling cash. It’s not the same as a highlighter, a regular pen, or a permanent marker, which don’t test authenticity and would simply leave ink on the bill or could damage it.