Ulysses S. Grant – 130

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You can really tell how smart these presidents really are when the ‘least smart’ president, Ulysses S. Grant, had an IQ of 130, which is still a full 15 points above the cutoff for the ‘average’ person. If this is the dumbest president then who on earth will be the smartest and what on earth will be their IQ?!

George W. Bush – 138.5

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George W. Bush always had a developed reputation for being one of the dumbest presidents to ever hold office. Sure, some of it was earned – he wasn’t exactly the best public speaker, with his invented words and saying things that were mainly meaningless – however an IQ of 138.5 is still decently high compared to the general population.

James Monroe – 138.6

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James Monroe was the last Founding Father to be elected as president. Maybe the reason he was last was due to his IQ ‘only’ being 138.6, compared to the rest of the Fathers? Monroe’s IQ just made it to third-lowest-score, however this doesn’t make him a slouch. An IQ of 138.6 is considered ‘very superior’ intelligent, according to the Wechsler IQ classification.

Andrew Johnson – 138.9

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Andrew Johnson became the president after Abraham Lincoln’s assassination, but he was the first president of the United States to be impeached. This was after his plans to restore the seceded states to the union (without granting protection to former slaves) came under fire in congress. The country certainly went onto elect smarter presidents after him.

William Howard Taft – 139.5

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Now, of course an IQ of 139.5 made William Howard Taft appear quite low on the smartness scale. However, he still remains to be the only person who has presided over both the executive and judicial branches of government. He held presidency from 1909-13, and then later became the 10th Chief Justice of the United States Supreme Court (1921-30).

James Buchanan – 139.6

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This rank of 139-ers is getting long! James Buchanan was the president during the lead-up to the Civil War. Perhaps if someone with a higher IQ was in the office instead of Buchanan, then the country wouldn’t have met its boiling point? Who knows? At least he got succeeded by a much smarter man afterwards.

Zachary Taylor – 139.8

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Every American soul knows this hero, nicknamed ‘old, rough and ready’ for his acts during the Mexican-American War. But clearly a mans abilities in battle don’t necessarily correlate with intelligence, since Zachary Taylor’s IQ of 139.8 is on the lower end of those who have held presidency.

Harry S. Truman – 139.8

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Falling in the lower 25% of president’s IQ is Harry S. Truman with an IQ of 189.8. This president for both the end of the World War II and the beginning of the Cold War, and was mainly known for his aggressive personality. Maybe he wasn’t so much known for his outstanding intelligence?

Warren G. Harding – 139.9

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Warren Harding’s presidency was cut short after he suffered a fatal heart attack in his third year in office. At the time, he died as one of the most popular presidents, however several scandals (Teapot Dome) made his reputation suffer a downfall following his death. He’s now considered one of the worst and least intelligent men to have ever held the office.

George Washington – 140

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Everyone knows George Washington, whether you’re from America or not. However, as a Founding Father and an absolute visionary, many people will believe that Washington is some sort of genius, and to a certain extent they would be correct. Of course, an IQ of 140 means he was way smarter than the average person back then in 1776, and even now. But he’s still not near the top of the list!