Once upon a time, if you were an avid user of bc(1) you where an avid user of dc(1). This is an extract of the Unix V7 man page for bc(1) https://man.cat-v.org/unix_7th/1/bc :

    Bc is actually a preprocessor for dc(1), which it invokes
    automatically, unless the -c (compile only) option is pre-
    sent.  In this case the dc input is sent to the standard
    output instead.