Question: How many men walked on the moon from the Apollo?
About the article "NASA", section "Project Apollo (1961–72)".

Candidate passages:
Twelve men have walked on the Moon – all American – eight of whom are still alive.
All of the landings took place between July 1969 and December 1972 as part of the Apollo program.
Regarding "the last man to walk on the Moon", Schmitt is the last person to step "onto" the Moon (as Cernan got out of the Apollo Lunar Module first), but Cernan is the last person to step "off" the Moon (after final EVA (extra-vehicular activity), Schmitt went inside the module first).
Duke was the youngest, at age 36 (+6mo); Shepard was the oldest, at age 47 (+2mo).
James A. Lovell, John W. Young and Eugene Cernan are the only three astronauts to fly more than one lunar mission (two each).
Of these three, only Lovell did not walk on the lunar surface.
Lovell and Fred Haise were prevented from walking on the Moon by the malfunction on Apollo 13 that resulted in the mission being aborted.
Haise was scheduled to walk on the Moon as commander of Apollo 19 prior to that mission’s cancellation on September 2, 1970.
Joe Engle had also trained to explore the Moon with Cernan as the backup crew for Apollo 14, but Engle was later replaced by geologist Harrison Schmitt when the primary crew for Apollo 17 was selected.
Schmitt had been crewed with Dick Gordon in anticipation for Apollo 18.
When Apollo 18 was canceled, Schmitt bumped Engle, leaving Gordon as the last Apollo astronaut who had trained extensively for lunar exploration without ever getting a chance to fly a lunar landing. 
Project Apollo (1961–72).
The U.S public's perception of the Soviet lead in putting the first man in space, motivated President John F. Kennedy to ask the Congress on May 25, 1961 to commit the federal government to a program to land a man on the Moon by the end of the 1960s, which effectively launched the Apollo program.
Apollo was one of the most expensive American scientific programs ever.
It is estimated to have cost $ in present-day US dollars.
(In comparison, the Manhattan Project cost roughly $, accounting for inflation.
)It used the Saturn rockets as launch vehicles, which were far bigger than the rockets built for previous projects.
The spacecraft was also bigger; it had two main parts, the combined command and service module (CSM) and the lunar landing module (LM).
The LM was to be left on the Moon and only the command module (CM) containing the three astronauts would eventually return to Earth.
The second manned mission, Apollo 8, brought astronauts for the first time in a flight around the Moon in December 1968.
Shortly before, the Soviets had sent an unmanned spacecraft around the Moon.
On the next two missions docking maneuvers that were needed for the Moon landing were practiced and then finally the Moon landing was made on the Apollo 11 mission in July 1969.
The first person to stand on the Moon was Neil Armstrong, who was followed by Buzz Aldrin, while Michael Collins orbited above.
Five subsequent Apollo missions also landed astronauts on the Moon, the last in December 1972.
Throughout these six Apollo spaceflights, twelve men walked on the Moon.
These missions returned a wealth of scientific data and of lunar samples.
Topics covered by experiments performed included soil mechanics, meteoroids, seismology, heat flow, lunar ranging, magnetic fields, and solar wind.
The Moon landing marked the end of the space race and as a gesture, Armstrong mentioned mankind when he stepped down on the Moon.
Apollo set major milestones in human spaceflight.
It stands alone in sending manned missions beyond low Earth orbit, and landing humans on another celestial body.
Apollo 8 was the first manned spacecraft to orbit another celestial body, while Apollo 17 marked the last moonwalk and the last manned mission beyond low Earth orbit.
The program spurred advances in many areas of technology peripheral to rocketry and manned spaceflight, including avionics, telecommunications, and computers.
Apollo sparked interest in many fields of engineering and left many physical facilities and machines developed for the program as landmarks.
Many objects and artifacts from the program are on display at various locations throughout the world, notably at the Smithsonian's Air and Space Museums.
In total, twenty-four U.S. astronauts have traveled to the Moon.
Three have made the trip twice, and twelve have walked on its surface.
Apollo 8 was a lunar-orbit-only mission, Apollo 10 included undocking and Descent Orbit Insertion (DOI), followed by LM staging to CSM redocking, while Apollo 13, originally scheduled as a landing, ended up as a lunar fly-by, by means of free return trajectory; thus, none of these missions made landings.
Apollo 7 and Apollo 9 never left Earth orbit.
Apart from the inherent dangers of manned Moon expeditions as seen with Apollo 13, one reason for their cessation according to astronaut Alan Bean is the cost it imposes in government subsidies. 
The Apollo program, also known as Project Apollo, was the third human spaceflight program carried out by the National Aeronautics and Space Administration (NASA), the United States' civilian space agency, and the program was responsible for the landing of the first humans on Earth's Moon in 1969.
First conceived during the Presidency of Dwight D. Eisenhower as a three-man spacecraft to follow the one-man Project Mercury which put the first Americans in space, Apollo was later dedicated to President John F. Kennedy's national goal of "landing a man on the Moon and returning him safely to the Earth" by the end of the 1960s, which he proposed in a May 25, 1961, address to Congress.
Project Mercury was followed by the two-man Project Gemini (1962–66).
The first manned flight of Apollo was in 1968.
Kennedy's goal was accomplished on the Apollo 11 mission when astronauts Neil Armstrong and Buzz Aldrin landed their Lunar Module (LM) on the Moon on July 20, 1969, and walked on its surface while Michael Collins remained in lunar orbit in the command spacecraft, and all three landed safely on Earth on July 24.
Five subsequent Apollo missions also landed astronauts on the Moon, the last in December 1972.
In these six spaceflights, 12 men walked on the Moon.
Apollo ran from 1961 to 1972, and was supported by the two-man Gemini program which ran concurrently with it from 1962 to 1966.
Gemini missions developed some of the space travel techniques that were necessary for the success of the Apollo missions.
Apollo used Saturn family rockets as launch vehicles.
Apollo / Saturn vehicles were also used for an Apollo Applications Program which consisted of three Skylab space station missions in 1973–74.
Apollo succeeded in achieving its goal of manned lunar landing, despite the major setback of a 1967 Apollo 1 cabin fire that killed the entire crew during a pre-launch test.
After the first landing, sufficient flight hardware remained for nine follow-on landings with an ambitious plan for extended lunar geological and astrophysical exploration.
Budget cuts forced the cancellation of three of these.
Five of the remaining six missions achieved successful landings, but the Apollo 13 landing was prevented by an oxygen tank explosion in transit to the Moon, which disabled the command spacecraft's propulsion and life support.
The crew returned to Earth safely by using the Lunar Module as a "lifeboat" for these functions.
Apollo set several major human spaceflight milestones.
It stands alone in sending manned missions beyond low Earth orbit; Apollo 8 was the first manned spacecraft to orbit another celestial body, while the final Apollo 17 mission marked the sixth Moon landing and the ninth manned mission beyond low Earth orbit.
The program returned of lunar rocks and soil to Earth, greatly contributing to the understanding of the Moon's composition and geological history.
The program laid the foundation for NASA's current human spaceflight capability, and funded construction of its Johnson Space Center and Kennedy Space Center.
Apollo also spurred advances in many areas of technology incidental to rocketry and manned spaceflight, including avionics, telecommunications, and computers. 
 Eugene Cernan, the last man who walked on the moon during the Apollo 17 mission Roger Clemens, former pitcher for the Houston Astros