Topic: 9s list of topics
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5 items are filed under this topic.

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	The cube root of 729		2014-11-12
		From Alexis: What would be the square root of 729 to the third power and could you explain how to get the answer? Answered by Penny Nom.
	Four 9s		2006-12-15
		From A student: Can you make 67 with four 9's without using the ceilling method? Answered by Stephen La Rocque.
	What's it called?		2004-04-22
		From Gerry: I'm a father and a grandfather and have come up with a game for my offspring to play while we're on the road. When we see a license plate, the object is to be the first one to add all the numbers on it, and come up with THE one digit number that sums them up. For example: ABC-787 = 7+8+7 = 22 = 2+2 = 4 Another example is 2932 = 2+9+3+2 = 16 = 1+6 = 7 Up 'til now, I've called it just plain "Numerology", but I'm sure that there's a math term for what we're doing, and I'd sure appreciate it if you could tell me what it is! Answered by Chris Fisher and Penny Nom.
	X.9999... and X+1		2003-08-23
		From David: I have read your answers to the questions on rational numbers, esp. 6.9999... = ? and still have a question: The simple algebraic stunt of converting repeating decimals to rational numbers seems to work for all numbers except X.999999.... where X is any integer. The fact that the method yields the integer X+1 in each case seems to violate the completeness axiom of the real numbers, namely that there is no space on the number line which does not have an number and conversely that every geometric point on the number line is associated with a unique real number. In the case of 3.999... for example, it seems that both the number 4 and the number 3.9999.... occupy the same point on the number line. How is this possible??? Answered by Penny Nom.
	Divisibility by 9		2000-10-24
		From Kelera: If the sum of the digits of a number is divisible by 9, then the number itself it divisible by 9. Why is that? How do you explain this? Answered by Penny Nom.

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