Posted by T.Gracken on September 16, 2002 at 20:53:10:
In Reply to: Decimal rounding - Grade 7 math - can anyone help? posted by Sunni Espinosa on September 16, 2002 at 19:08:47:
: My son has the following question and I have no idea how to figure it out because I'm over 50 and we didn't do math like this back then. Any help is greatly appreciated.
: Here is the question:
: Round to the number 34.1834 to these place values:
: a) to the nearest tenth
: b) to the nearest hundreth
: c) to the nearest thousandth
: d) to the nearest one
: Your help is greatly appreciated.
: Sunni
I don't know where you are from, but me and those I know certainly did math like this "back then" and still do now.
in any case,
you first need to understand place values.
from right to left (from the left of the decimal point) -- > ones, tens, hundreds, thousands, ten thousands, hundred thousands, millions, etc.
from left to right (from the right of the deminal point) -- > tenths, hundredths, thousandths, ten thousandths, hundred thousandths, millionths, etc.
now, to round to the nearest place value means to figure out what number is closest (if you were counting by that place value)
for example, to round to the one's place means what number is closest to the given number if you were counting by 1's (you know, 1,2,3,4,...)
to round to the ten's would mean what number is closest if you counted by 10's (10,20,30,etc)
to round to the tenth's would mean what number is closest if you counted by tenths (1, 1.1, 1.2, 1.3, etc)
so one common method is to determine the place value you want to round to. then find it in the number and look to the digit immediately right of that place. If the digit to the right is less than 5, then erase all digits to the right of the place value. If the digit is 5 or above, erase all digits to the right of the place value and add one to the place value.
so for the number 34.1834
if you want to round to the nearest tenth:
(notice the digit 1 is in the tenth's place and the digit immediately right is 8. since 8 is "5 or bigger", we will erase all digits right of 1 and add 1 to 1)
the answer is 34.2
if you want to round to the nearest hundredth:
(notice the digit 8 is in the hundredth's place and the digit immediately right is 3. since 3 is "less than 5", we will erase all digits right of 8)
the answer is 34.18
try the rest on your own
...or better yet, have your son try the rest on his own.