Bash : extracting part of a string

Question

Say I have the string \"Memory Used: 19.54M\" How would I extract the 19.54 from it? The 19.54 will change frequently so i need to store it in a variable and compare it with

Answer 1

> echo "Memory Used: 19.54M" | perl -pe 's/\d+\.\d+//g'
Memory Used: M