it's -2.356 divided by -0.02.
i got 117.8.
my friend tells me it's 117.5
but i still get the same answer.
help. this will help if u post it till monday. 7:20am
thanks.
2007-09-09 11:50:21 · 25 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
You are right (117.8)
2007-09-09 11:54:00 · answer #1 · answered by Tom :: Athier than Thou 6 · 0⤊ 0⤋
With friends like that, who needs mathematical enemies?
The answer is clearly 117.8; and here's how to tell it MUST end in 8:
ANY number ending in 6 that is divided by a number whose significant part is the digit ' 2 ' MUST end in 3 or 8.
Thus: 06, 26, 46, 66, 86 divided by 2 are 03, 13, 23, 33, and 43; that is [2n]6 / 2 = [n]3, where [...] means "the single digit with this value."
16, 36, 56, 76 and 96 divided by 2 are 08, 18, 28, 38 and 48; that is [2n + 1]6 / 2 = [n]8, where [...] again means "the single digit with this value."
As you can see, that divides the digits preceding the 6 into either an even set or an odd set of digits.
Correspondingly, if the 100's digit is EVEN, that won't affect the possible endings shown above; if the 100's digit is ODD, then 50 will be added to all the possibilities listed for the last two digits of the result. THAT'S how you get possibilites larger than 50 as the final two digits, such as 83 or 68 or your own 78.
Of course, all this is just theorising about it, as a mental TEST of whether your friend's claim could POSSIBLY be correct. But the division is in fact so simple that the best test is just provided by DOING IT! Nevertheless, simple mental tests like this not only keep YOU alert, they also act as a check against the possibility of having mispunched a problem into a calculator. (I confess that in analogous ways, I'm aware of a few per cent personal error in punching calculations into a calculator.)
Live long and prosper.
2007-09-09 11:56:07 · answer #2 · answered by Dr Spock 6 · 0⤊ 0⤋
move the decimal points so that -.02 is a whole number so it's -235.6 divided by -2. then you do the division and you get 117.8.
I think you're friend is wrong. I even did it on a calculator.
2007-09-09 11:54:42 · answer #3 · answered by Like Woah 3 · 0⤊ 0⤋
The correct answer is 117.8 , another way to analyszed the problems is 235.6 divide by 2
same answer
2007-09-09 11:55:07 · answer #4 · answered by kerga 2 · 0⤊ 0⤋
I think your friend is an idiot. Let's modify the problem a litte to make the math easier. Mulitply both sides by -1: 2.356/ .02. Multiply both sides by 100. 235.6/2. 2/2 = 1; 35.6/2 = 17.8. --> 117.8. So, you are right, your friend should go back to school.
2007-09-09 11:59:52 · answer #5 · answered by imh400 3 · 0⤊ 0⤋
I tried it so many ways and i came up with the same answer as you, 117.8
2007-09-09 11:54:49 · answer #6 · answered by erniemigi 3 · 0⤊ 0⤋
I did it longhand (with pencil and paper), and on 3 different calculators and 2 different computers. And I got 117.8 every time.
Doug
2007-09-09 11:59:05 · answer #7 · answered by doug_donaghue 7 · 0⤊ 0⤋
I got 117.8 when using a calculator.
2007-09-09 11:54:22 · answer #8 · answered by Music Lover 2 · 0⤊ 0⤋
i think you got the right answer, i put this number in my TI-89 calculator which the percentage of error is really really small. and the answer i got is 117.8. if your friend still say you got the wrong answer, ask his/her what wrong with it and ask his/her to explain how the answer is 117.5
2007-09-09 11:58:22 · answer #9 · answered by cybersoro 1 · 0⤊ 0⤋
You're right. It's 117.8.
2007-09-09 11:55:40 · answer #10 · answered by Anonymous · 0⤊ 0⤋