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Q:

# Can you make 100 using four nines?

A:

A person can make 100 using the digit 9 four times in an equation. The equation for this math problem is: 99 + (9 / 9) = 100. This solution works because 9 divided by 9 equals 1, and 99 plus 1 equals 100.

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Solving this math problem requires one to notice that the number 99, which contains the digit 9 repeated twice, is very close to 100. In fact, 100 - 99 = 1. The other two 9 digits must therefore equal one, and this requires a fraction. The fraction 9 over 9 equals 1. Combining these two facts in a single equation solves this math problem, with the answer being 99 + (9 / 9) = 100.

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## Related Questions

• A:

The most common prefix for the number nine is "nona-", such as in the word "nonagon," which describes a polygon with nine sides, and "nonagenarian," a person in his 90s. A less commonly used prefix is "nove-," as in "novennial," which is an event that occurs every nine years.

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• A:

A person who lives to be 100 is a centenarian. In 1980, there were 32,000 centenarians in the United States, but the number grew to over 52,000 by 2010, an increase of over 65 percent, while the general population grew by 32 percent.

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• A:

A math genius is a person who is exceptional in the field of mathematics. Someone considered to be a genius typically has skills and understanding in their field far above those of most people. In many cases, the term is applied to those whose talent in a field allows them to achieve a new level of insight that benefits humanity.