Title: Cristiano Ronaldo
Content:  Ronaldo's move to Manchester United was completed on 12 August 2003, too late for the 2003 FA Community Shield but in time for their game against Bolton Wanderers on the opening day of the 2003–04 season, and made him the first Portuguese player to sign for the club. His transfer fee of £12.24 million made him, at the time, the most expensive teenager in English football history. Although he requested the number 28, his number at Sporting, he received the squad number 7 shirt, which had previously been worn by such United players as George Best, Eric Cantona and David Beckham. Wearing the number 7 
Title: Cristiano Ronaldo
Content:  On 27 August 2021, Manchester United announced they had reached an agreement with Juventus to re-sign Ronaldo, subject to agreement of personal terms, visa and medical. The transfer was reported as costing an initial £12.85 million, with a two-year contract plus an optional year, and was confirmed on 31 August. Ronaldo was given the number 7 shirt after Edinson Cavani agreed to switch to 21. The first 24 hours of Ronaldo's shirt sales was reported to have broken the all-time record following a transfer, overtaking Messi after his move to Paris Saint-Germain. On 11 September, Ronaldo made his second debut at Old Trafford, scoring the opening two goals in a 4–1 league victory against Newcastle United. On 29 September, he scored a last-minute winner in United's 2–1 victory at home to Villarreal in the Champions League, and overtaking Iker Casillas as the player with the most appearances in the competition. On 2 December, Ronaldo scored twice in a 3–2 home league win against Arsenal, taking him past 800 top-level career goals.
Title: Cristiano Ronaldo
Content:  in November to discuss a possible transfer. Manchester United manager Alex Ferguson was determined to acquire Ronaldo on a permanent move urgently, after Sporting defeated United 3–1 at the inauguration of the Estádio José Alvalade in August 2003. Initially, United had planned to sign Ronaldo and loan him back to Sporting for a year. Having been impressed by him, the United players urged Ferguson to sign him. After the game, Ferguson agreed to pay Sporting £12.24 million for what he considered to be "one of the most exciting young players" he had ever seen. A decade after his departure from the club, in April 2013, Sporting honoured Ronaldo by selecting him to become their 100,000th member.
Title: 2021–22 Manchester United F.C. season
Content:  The 2021–22 season is Manchester United's 30th season in the Premier League and their 47th consecutive season in the top flight of English football. The club is participating in the Premier League, the FA Cup and the UEFA Champions League, having been knocked out of the EFL Cup in the third round. In August 2021, Cristiano Ronaldo returned to the club from Juventus after 12 years away, having left for Real Madrid in 2009 for a world record transfer fee. On 21 November 2021, manager Ole Gunnar Solskjær left the club and was replaced as caretaker by first-team coach Michael Carrick. Eight days later, Ralf Rangnick was appointed as interim manager until the end of the season, taking charge officially on 3 December.
Title: June 2009 in sports
Content: Manchester United F.C. accepts an offer for a record €93.9 million (£80 million, US$132 million) transfer fee from Real Madrid C.F. for the services of Cristiano Ronaldo. Ronaldo has until June 30 to accept a contract from Real Madrid. (ESPN Soccernet) 
Title: Ramón Calderón
Content:  Ronaldo to the club, but failed in doing so as the player wanted to stay one more year at Manchester United. Finally, on 12 December 2008, he managed to sign the contract with the Portuguese player for the next 6 years, after having agreed a transfer fee of €94 million with United. Calderón was major proponent and driving force behind the club's social and institutional transformation. While at the helm, he strengthened Real Madrid's social responsibility programs as well as the activities of its Foundation (where he is currently a Member of the Board) opening several Academies around the world to help children improve their lives. During his Presidency, the club 
Title: Cristiano Ronaldo
Content:  an extra source of motivation for Ronaldo. A key element in his development during his time in England proved to be Ferguson, of whom he later said: "He's been my father in sport, one of the most important and influential factors in my career." Ronaldo made his debut as a substitute in a 4–0 home win over Bolton in the Premier League on 16 August 2003, and received a standing ovation when he came on for Nicky Butt. His performance earned praise from Best, who hailed it as "undoubtedly the most exciting debut" he had ever seen. Ronaldo scored his first goal for Manchester United 
Title: 2009–10 Manchester United F.C. season
Content:  United announced early in the transfer window that they had agreed a world record fee of £80 million to sell Cristiano Ronaldo to Real Madrid. Shortly after this, they confirmed that Carlos Tevez, who had been on loan with the club for two seasons, had not taken up the offer of a permanent contract. Tevez would later sign for United's local rivals, Manchester City. Lee Martin, Fraizer Campbell, Richard Eckersley and Manucho also left the club for an undisclosed fee. After the departures of Ronaldo and Tevez, United sought a new striker, and Karim Benzema (who eventually signed for Real Madrid) was one player they courted. Despite the record deal for Ronaldo, United opted for a cheaper deal in 
Title: History of Manchester United F.C. (1986–2013)
Content:  the team were 8 points behind leaders Arsenal at the beginning of March, when they also lost the League Cup final to Liverpool. Soon afterwards, David Beckham was sold to Real Madrid for £25 million, following arguments with Ferguson. Before the start of the season, a highly rated 18-year-old Portuguese winger called Cristiano Ronaldo arrived from Sporting CP for £12.24 million. All eyes that summer, however, were on a Chelsea side who had been taken over by Russian billionaire Roman Abramovich and had spent more than £100 million on new players. In the 2003–04 season, Manchester United won the FA Cup for the 11th time 
Title: History of Manchester United F.C. (1986–2013)
Content:  their history, but after Rio Ferdinand received an eight-month suspension for failing to attend a drugs test, the club finished third in the Premier League, which was won by an unbeaten Arsenal, while second place went to Chelsea. Just after the start of the 2004–05 campaign, the club signed highly regarded teenage striker Wayne Rooney from Everton for £25.6 million. The club reached the FA Cup Final again but were beaten by Arsenal in a penalty shoot-out, the first time that the FA Cup Final had been decided on penalties. Chelsea finished the season as Premier League champions, while Arsenal finished second and United third.

Question: when did cristiano ronaldo go to manchester united?
Answer: 2003.
at age 18 in 2003.