MattL
09-11-2006, 09:24 PM
I upset one of the math teachers at our school today. I teach industirial tech to 7th and 8th graders. The year starts out with a mechanical drafting unit, we have been working on how to use a ruler. My list of project drawings requires the kids to convert decimal units to fractions so they can use our rulers. In going over this we use a conversion chart I got from my drafting book.
I remember as a kid that if you needed to round off a number, say to the nearest tenth, that if the 100's are 6 or greater you round up, 4 or less you round down. The problem is with 5, I was taught, and the drafting book supports that if the tenths are odd and the hundreths are 5 you round up. If the tenths are even you round down. I remember this as the way I learned it too, I was in science classes in college and I remember this there too.
Now it seems the rule in math classes is that if the 100s are 5 you round tenths no matter what. To me this is statistically wrong. What is the concensis here?
I remember as a kid that if you needed to round off a number, say to the nearest tenth, that if the 100's are 6 or greater you round up, 4 or less you round down. The problem is with 5, I was taught, and the drafting book supports that if the tenths are odd and the hundreths are 5 you round up. If the tenths are even you round down. I remember this as the way I learned it too, I was in science classes in college and I remember this there too.
Now it seems the rule in math classes is that if the 100s are 5 you round tenths no matter what. To me this is statistically wrong. What is the concensis here?