Sxiyuan wrote:But 4/8=1/2=0.5 .Apparently,its tenth digit is 0
Hi! I'm assuming that this last part in quotes is your actually comment/question.
It's important to know the place names for the various digits in a numbers, so let's do a quick review, using the example of:
12345.6789
We start numbering to the left and the right of the decimal place. Let's start on the left!
5 = ones or units digit
4 = tens digit
3 = hundreds digit
2 = thousands digit
1 = ten thousands digit
and to the right:
6 = tenths digit
7 = hundredths digit
8 = thousandths digit
9 = ten thousandths digit
Here's another way to think about the digits:
the numbers to the left of the decimal get MULTIPLIED by their digit name; and
the numbers to the right of the decimal get DIVIDED by their digit name.
So, going back to our example of 12345.6789, we could express that number as:
1*10000 + 2*1000 + 3*100 + 4*10 + 5*1
+
6/10 + 7/100 + 8/1000 + 9/10000
Hence the names for the digits!
As an aside, you'll notice that there's no "oneths" or "unitths" digit - that's because there's no number to the right of the decimal that you divide by 1 to get it's value. They're also silly-sounding words!
I hope that clears things up,
Stuart