We propose a simple and powerful predictive interface technique for text editing tasks. With our technique called the dynamic macro creation, when a user types a special "repeat" keyafter doing repetitive operations in a text editor, an editing sequence corresponding to one iteration is detected, defined as a macro, and executed at the same time. Although being simple, a wide range of repetitive tasks can be performed just by typing the repeat key. When we use another special "predict" key for conventional prediction techniques in addition to the repeat key, wider range of prediction schemes can be performed depending on the order of using these two keys.