this is a really cool thing but how does it work. Please explain the rule behind it aka the concept.
2006-07-05 07:13:27 · 6 answers · asked by mrsdamico22 3 in Science & Mathematics ➔ Mathematics
It's actually pretty easy. When you take a number, jumble around it's digits and then subract the new number from the old, you are always going to get a difference divisible by 9. Since 9 divides the sum of the digits of all numbers divisible by 9, then nine divides the sum of the digits of the difference. When you give all but one of the digits (and knowing that the last one is not 0), the computer just takes the sum of the digits you gave it, and subtracts it from a multiple of 9 (so that the remainder is between 1 and 9). The number that you picked will always be the remainder.
2006-07-05 07:34:52 · answer #1 · answered by Eulercrosser 4 · 1⤊ 1⤋
Simple mathematics. Based on certain rules, like he knows the 2 numbers you are subtracting have the same digits in them, so your answer there will fall within a certain range.
Follow the process through very carefully on paper, using different numbers, and you will start to see the pattern he uses.
2006-07-05 14:19:54 · answer #2 · answered by Mike M 1 · 0⤊ 0⤋
It's based on casting out nines, see for instance http://mathforum.org/library/drmath/view/55831.html
2006-07-05 14:59:25 · answer #3 · answered by Stephan B 5 · 0⤊ 0⤋
i think the hints meant something with squares or square roots...it was pretty cool.
2006-07-05 14:19:05 · answer #4 · answered by wickedblack67 2 · 0⤊ 0⤋
Good question. It is cool!
2006-07-05 14:17:26 · answer #5 · answered by Anonymous · 0⤊ 0⤋
i dunno, sorry.
2006-07-05 14:16:35 · answer #6 · answered by Anry 7 · 0⤊ 0⤋