We tested a procedure for memorizing long strings of digits. As a preliminary step, two subjects memorized a substitute word for each of the 100 possible digit pairs by using the digit-consonant mnemonic. Next, for each string to be memorized, successive pairs of digits were encoded into their corresponding substitute words. These words were then memorized using the story mnemonic. To reduce forgetting of long, 80-digit strings, a hierarchical story mnemonic was developed. In this procedure, each successive set of 10 words (20 digits) was organized into a story episode that occurred in a predetermined location. The location served as a context cue during recall. An experiment in which a practiced subject memorized 80-digit strings showed that recall with the hierarchical story mnemonic (99.1%) was superior to the unstructured story mnemonic (92.2%). The procedure and results of this experiment are compared with those of Chase and Ericsson (1981) and Kliegl, Smith, Heckhausen, and Baltes (1987).