multiply vs step up

multiply

verb
  • To increase the amount, degree or number of (something). 

  • To grow in number. 

  • To perform multiplication. 

  • To be a factor in a multiplication with (another factor). 

  • To breed or propagate. 

  • To perform multiplication on (a number). 

noun
  • An act or instance of multiplying. 

adv
  • In many or multiple ways. 

step up

verb
  • To increase, augment, or advance, especially by one or more steps. 

  • To assume or take responsibility. 

How often have the words multiply and step up occurred in a corpus of books? (source: Google Ngram Viewer )