You look up the number for pizza hut and repeat it several times in your head until you can find a place to write it down. the process of actively repeating the number is

The process of actively repeating the number is called rehearsal.

Explanation:

A rehearsal can be described as an art which you practice again and again so that you become ready for a public performance or for using that skill for a final-end purpose.

In the following mentioned scenario, a person looks up the number for Pizza Hut and repeats it which is a type of rehearsal. Depending on the situation, a rehearsal can be done for a single time or for many time according to the need of a person.