Wales romped to their biggest ever Six Nations win - and handed Scotland their record defeat in the Championship in the process - as they ran in seven tries against a visiting side reduced to 14 men when Stuart Hogg was red carded.
The Scottish full-back was dismissed in the 22nd minute for a late shoulder charge on Wales fly-half Dan Biggar, with the hosts leading 10-3 at that point.
Referee Jerome Garces initially showed Hogg a yellow card, but changed it to a straight red after watching a replay on the stadium big screen.
Wales exploited the extra man with tries by George North (2), Jamie Roberts (2), Taulupe Faletau, Liam Williams and Rhodri Williams.
Greig Laidlaw's fourth minute penalty briefly gave Scotland the lead, while Biggar kicked two penalties and four conversions, with James Hook adding a fifth.
It completed a disastrous Six Nations for the Scots, whose previous heaviest defeat in the tournament was their 38-3 defeat by France in 2003, with a narrow win in Rome their only reward for a disappointing campaign.
And new coach Vern Cotter, who will take over before their tour to North America in the summer, will be under no illusion about the size of the task he faces.
Wales' victory margin of 48 points exceeded their previous record winning margin, which came in the 47-8 win against Italy in 2008, by 11 points.
It also doubled their previous best over the Scots, in the 46-22 win during their 2005 Grand Slam season.
But there will be no Grand Slam or third consecutive title for the Welsh this season, and the fact they played against 14 men for an hour will cast some doubt over the significance of this performance, coming after their poor display in the 29-18 loss against England.
It was, however, a fitting tribute to Wales loose-head Gethin Jenkins, who became his country's most-capped player on his 105th appearance.
Scotland were trailing 10-3 when Hogg - chasing his own high kick - caught Biggar on the jaw with a shoulder charge.
Referee Garces quickly handed the British and Irish Lion a yellow card, but called the player back on to the pitch and showed him a straight red after watching replays of the incident on the stadium screens.
Hogg did not complain as he became the third Scotsman to be sent off in internationals - following in the footsteps of Scott Murray and Nathan Hines - and the Scottish challenge ended with his departure.
Until that point Scotland had been competitive, although the Welsh pack had shown ominous signs of recapturing the power game which made them Six Nations champions in 2012 and 2013, particularly in the build-up to Liam Williams' opening try.
After Hogg's dismissal, Wales changed their emphasis - attacking out wide to exploit the extra man and the power of their three-quarter line and full-back Williams, making an impressive appearance in the absence of the injured Leigh Halfpenny.
Tries by North, after a superb break by Williams, and Roberts before half-time underlined the size of Scotland's task.
And when Faletau touched down for the sixth try in the 53rd minute it was a question of damage limitation, which the battling Scots achieved until substitute scrum-half Rhodri Williams crossed for his team's seventh in the 75th minute.
The cheers that greeted James Hook's conversion were an amusing post-script, but the serious lesson was that you cannot take on an international side with only 14 players.
And with cameras covering every angle, match officials are increasingly willing to use replays to amend their decisions.
For Scotland in Cardiff, there was nowhere to hide.
Wales: L Williams; Cuthbert, Davies, Roberts, North; Biggar, M Phillips; Jenkins, Owens, R Jones, Charteris, A Jones, Lydiate, Warburton, Faletau.
Replacements: Hook for L Williams (63), Priestland for Biggar (63), R. Williams for M. Phillips (55), James for Jenkins (58), Hibbard for Owens (58), A Jones for R Jones (58), Ball for Charteris (63), Tipuric for Lydiate (55).
Scotland: Hogg; Fife, Dunbar, Scott, Evans; Weir, Laidlaw; Grant, Lawson, Cross, R Gray, Hamilton, Wilson, Brown, Denton.
Replacements: Taylor for Fife (67), Cusiter for Laidlaw (62), Dickinson for Grant (46), Ford for Lawson (46), Swinson for Hamilton (55), Strokosch for Brown (9).
Not Used: Murray, Cuthbert.
Sent off: Hogg (23).
Ref: Jerome Garces (France).