KRL extended quotes support the beesting operator, making them simple templating systems. Inside an extended quote, expression values can be referenced using the #{<expr>} syntax. For example, suppose you've stored 10 and 20 in the variables a and b:
somevar = <<
The average of #{a} and #{b} is #{(a+ b)/2}
>>;
The value of somevar would be "The average of 10 and 20 is 15."