The 1004 Coin Scam is a scam in which the scammer lowers the amount of coins offered in a trade and gets the item for a very low price. This works because 1004 looks so much like 100k in the trade window. An example of this scam: Player A offers to buy item x for 100k. Player B trades. Player A offers 100k, Player B offers item x. Before both players accept, however, player A changes 100k to 1004 coins. Player B and Player A accept, and player B gets scammed.

This scam has become relatively extinct since Jagex changed the color of the numbers on a cash pile if it's more than 1000 coins. Mostly new players still might fall for it.