A more charitable explanation for Trump would expand the number to include those people who are working part time because they can't find full-time work, all the unemployed and those marginally attached to the workforce. This broader measure of slack in the economy, known as the U6, is about 14.7 million. It's the lowest since May 2008, and has come down by nearly 12 million since the worst of the job market effects of the financial crisis in 2010. And remember, many of these folks have work, though it's part time.
If that's what the president-elect means, he's then only off by 82 million. What about the rest? Perhaps some want jobs, but that's not what is shown in the data, gathered from a monthly survey of some 60,000 Americans. Some are in school. The "not in the labor force" number includes those 16 to 21, prime school age. About 6 percent of the public reported in a 2014 study by the Bureau of Labor Statistics that they are not in the labor force because they are going to school.