When your subtracting mesurments like 4' - 7' 1/2" how do you do that?

Do I convert the fraction to a decimal and subtract?
Thanks

I'd keep the fractions, but change the denominators to a common one.

Example:

4' 7 1/2 inches minus 3' 2 1/4 inches

............4' 7 2/4 " (this is equal to 4' 7 1/2" because 1/2 = 2/4)
..........- 3' 2 1/4"
..........___________
............1' 5 1/4"

Does that help, or just make it worse?

Last edited: Tuesday, December 06, 2005 at 7:09:05 PM

Got it, thank you every much LGM B)
Wait one more Question when you subtrating a fraction like 5' 1/2"- 8' 1/2" what happens with the hafes?

Last edited: Tuesday, December 06, 2005 at 7:53:36 PM

Nice instructions LGM, are you a math teacher?
Another way to do that is to get out a ruler.

1/2 minus 1/2 = 0

8 - 5 = 3

So, it's 3. Or, count up... Start at 5 1/2, then 6 1/2, 7 1/2, and 8 1/2. Count 3 up.

The reason I don't do decimal conversions is because measurement tools aren't usually calibrated in tenths. Mathematically, that works fine, but trying to measure 3.675" with a tape or ruler isn't so friendly.

One way to do it is with decimals, but I like how LG does it too.
I'm just used to decimals :)
..8' 1/2" = 8.5
- 5' 1/2" = 5.5
--------------------
3 and no halfs

Wait, did you mean for it to make a negative number, or did I do it right?

Last edited: Tuesday, December 06, 2005 at 8:10:10 PM

Thanks elf, I teach 5th grade... So yeah, that math is part of it.

Niiiice, I liked 5th grade

Me too... I've been in it for over a decade now... ;)