#!/usr/bin/perl -w
use strict;

local $/ = "";   # paragraph mode

while (<DATA>) {
    my ($num) = /^(\d+)/;
    s/\w+/$num/g;
    print;
}

__DATA__
0       ASDF
        ASEE
        ASEE

13      DERG
        DREG

28      QWER
        QWER

42      WERT
        WERT
        WERT

55      QWEASD
        QWEASD
        QWEASD
        QWEASD