Sujet: nine liste de sujets
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31 articles trouvés pour ce sujet.

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	preuve par 9		2001-04-04
		Michel pose la question : Pourriez-vous m'expliquer en détail comment fonctionne la preuve par 9 (pour une division et une multiplication). Je sais l'appliquer mais je ne sais pas pourquoi ça marche. Je ne retrouve pas la démonstration. Merci de m'aider. Exemple . 17x2=34 ; preuve par neuf : 1+7=8 ; 8x2= 16 ; 1+6=7 et 3+4=7, on peut donc supposer (sans affirmer) que cette multiplication a un résultat juste car la preuve par 9 est bonne, 7=7. Comment fonctionne cette preuve par 9??? Claude Tardif lui répond.
	Combien y aura t il de 9 dans la réponse?		2000-06-17
		Marie pose la question : J'ai lu une énigme mais je n'ai pas la réponse."si l'on divise 123 456 789 par 999 999 999, combien y aura t il de 9 dans la réponse?" Claude Tardif lui répond.
	The cube root of 729		2014-11-12
		Alexis pose la question : What would be the square root of 729 to the third power and could you explain how to get the answer? Penny Nom lui répond.
	Numbers with a digit 9		2011-05-13
		Veronica pose la question : How many numbers between 200 and 750 have a 9 for at least one of the digits? Penny Nom lui répond.
	Six nines		2010-09-16
		Steph pose la question : It's sort of one question. We have to use six nines to get the numbers 1-30. I got all but 22, 23, 24, and 30. Like 15 is 9+9-(9+9+9)/9. Penny Nom lui répond.
	A magic/math trick		2009-12-04
		Valentin pose la question : What is the explanation for the following math trick: you think of any four digit number add those digits take that sum and subtract it from the first number then you say three of those new numbers in any order and the other person guesses the last digit. How does he do it? Claude Tardif lui répond.
	The sum of digits of 4444^4444		2009-08-31
		SHIVDEEP pose la question : The sum of digits of 4444^4444 is A .The sum of digits of A is B . Find the sum of digits of B ? Claude Tardif lui répond.
	Four nines to make 100		2008-11-27
		jane pose la question : use 4 nines in a math equation that will give you an answer of 100 Penny lui répond.
	A 9 team flag football tournament		2008-05-22
		James pose la question : I like to run a 9 team flag football tournament where each team is guaranteed 3 games prior to playoffs. All games must have playoff implications and must not be a consolation game. Victoria West lui répond.
	A season schedule for 9 teams		2008-05-22
		James pose la question : would like to put together a season schedule for 9 teams with each team playing three or 4 games leading to a 1 to 9 ranking. Victoria West lui répond.
	Nine digit numbers		2008-05-21
		Alex pose la question : List of Nine digit numbers, that can be divided by nine? Janice Cotcher lui répond.
	A math trick		2007-12-10
		Megan pose la question : I need to write a mathematical explanation of why this works! Start with a four digit number. (a positive integer, and all digits can NOT be the same. At least one must be different) Rearrange that four digit number. Subtract the smaller 4-digit number from the larger. Now circel one digit. (canNOT be zero, because that is already a circle) Now re-write that number excluding the circled digit. Compute the sum of the digits. Now write down the next multiple of 9 that is larger than the sum. Subtract the Sum from the multiple. (multiple - sum of digits) Report Difference = to number circled. The resulting number should be the number that originally circled. Penny Nom lui répond.
	Nine dots		2007-09-25
		al pose la question : Connect the dots. There is nine dots, three across and three down. Connect the nine dot with the pencil only using four line and never lifting the pencil off of the paper. Stephen La Rocque and Harley Weston lui répond.
	Four 9s		2006-12-15
		A student pose la question : Can you make 67 with four 9's without using the ceilling method? Stephen La Rocque lui répond.
	A number puzzle		2006-03-22
		A teacher pose la question : Students brought this website to my attention and asked why this puzzle worked... I'm not sure. The url is: http://digicc.com/fido/ and it tells you to choose a 3 or 4 digit random number with different digits. Write it down, rearrange, subtract the smaller from the larger. then circle a nonzero digit, type the remaining digits into the space provided and they will tell you the number you circled. Can you provide the reason that this works. Claude Tardif and Penny Nom lui répond.
	Back to the nines		2006-03-15
		Victoria pose la question : Can you answer this problem, does an answer exist? Get a set of numbers 1-9 ! Using the whole set of nine number tiles (digits 1-9), try to arrange them to make three 3-digit numbers so that the sum of the first two is the third. Can this be done without carrying over? If not can it be done without carrying over into the hundreds column? Claude Tardif lui répond.
	Nine minutes		2004-09-02
		A student pose la question : You have two hour glasses-one measures 7 minutes and one measures 4 minutes.How can you time 9 minutes? Penny Nom lui répond.
	Pick a number greater than 1		2004-06-25
		A student pose la question : I understand that when you pick a number greater than 1 and less than 10; multiply it by 7 and add 23, then add the digits of that number until you get a one digit number. Then multiply that number by 9, add the digits of that number until you get a one digit number, subtract 3 from that number and divide the difference by 3; that this process will always give you the result of 2. Does this have a name or theory for it as to why the answer will always be 2? Penny Nom lui répond.
	What's it called?		2004-04-22
		Gerry pose la question : 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! Chris Fisher and Penny Nom lui répond.
	X.9999... and X+1		2003-08-23
		David pose la question : 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??? Penny Nom lui répond.
	nine digit numbers		2003-07-23
		John pose la question : With a nine digit number, with each of the nine digits having a possibility of 10 different numbers then what is the total number of possible mathematical variations in the nine digit number. i.e. Social Security numbers have nine digits and if each of the nine digits have a possibility of being any one of ten numbers, i.e. 0,1,2,3,4,5,6,7,8,9. Then what is the formula to calculate the maximum possible number of variations in this nine digit number and what is the mathematical maximum possible number of variations of this nine digit number? Penny Nom lui répond.
	A group of 9		2002-08-31
		William pose la question : what is the mathmatical name for a group of nine like a group of 3 is called 'triplets' Penny Nom lui répond.
	100 from four 9's		2002-03-27
		A student pose la question : My teacher gave us a math problem to try and figure out and I am stumped. The problem was this.... by only using four nines, how can you get an answer of 100? You can add, subtract, multiply or divide...anything you need to do ,but you can only use four nines. Leeanne Boehm lui répond.
	How do you get to 100 by using 6 nines?		2001-11-17
		A student pose la question : How do you get to 100 by using 6 nines? Claude Tardif lui répond.
	Six nines		2001-10-09
		A mom pose la question : My middle schooler (sixth) has to calculate the integers 0-20 using only 6 nines. We have done all but the integer 14. He can not use decimals or double the nine like 99 or 19. the fraction 9/9 is okay. Keep in mind of course the order of operations. Claude Tardif lui répond.
	Divisibility by 9		2000-10-24
		Kelera pose la question : 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? Penny Nom lui répond.
	Divisibility by 3		2000-03-24
		Pat Walsh pose la question : W hy does it work when you add the digits of a number then divid by three to see if the number is divisible by three Penny Nom lui répond.
	Nines and ones		1999-11-05
		Greg Miller pose la question : Using the numbers 1, 1, 9, 9, only once each, how can I create an expression that equals 10 using only the basic functions of addition, subtraction, multiplication, division, and/or parentheses? Claude Tardif lui répond.
	Divisibility by 9		1999-02-21
		Razzi pose la question : I've been having a hard time trying to solve the following problem and I was wondering if you could help me. For any positive integer a let S(a) be the sum of its digits. Prove that a is divisible by 9 if and only if there exist a positive integer b such that S(a)=S(b)=S(a+b). Chris Fisher and Harley Weston lui répond.
	A Place Value Curiosity		1998-05-25
		Ed pose la question : I was visiting with an elderly gentleman this afternoon. He showed me this curiosity and then asked if I could explain it to him. Can you provide an explanation of why the 9 or multiple of 9 keeps occurring in this procedure? Choose any number, say 125 and add the digits to get 8. subtract the 8 from the 125 and the result is 117. Add the digits in 117 to get 9. Subtract the 9 from the 117 to get 108. Add the digits in 108 to get 9. If this procedure continues a 9 or a multiple of 9 reoccurs. What is the mathematical explanation behind this happening? Denis Hanson lui répond.
	Multiplying by Nine - Chismbop Style		1998-04-27
		Noria Jones pose la question : About a year ago a grade 5 teacher at my son's school taught the children how to multiply the 9 times table on their fingers quickly. It was part of a kind of finger math kind of thing... Patrick Maidorn lui répond.

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