With your number-word dictionary from Day 9 in hand, long digit strings stop being scary. The method: break the string into two-digit chunks, convert each chunk to its picture-word, then chain the words together into one moving story, exactly like Day 3’s Story Chain.
Take a ten-digit phone number: split it into five two-digit chunks. Convert each chunk to its word. Now link word one to word two with an absurd action, word two to word three, and so on. To recall the number, walk the story and convert each picture back into its digits.
This same chunk-and-chain approach works for PINs, account numbers, addresses, anything numeric. The only thing that changes as strings get longer is how many chunks you’re chaining, the technique itself never changes.