I'm taking a class called Dosage Calculations. I am having fits with the apothecary system (changing those measurements to metric and metric to apothecary). The fractions are the worst...changing something like gr 1/150 to mg, and stuff like that. Is there an easy way of mastering this?

"Easy," I don't know.

Lots of practice is about the best I can offer. Be sure you have all your conversion factors memorized and then do a zillion problems until you have 'em down pat.

Do you understand the basics of ratios and working with fractions (multiplication, division, cross-multiplying, canceling, etc)?

"Easy," I don't know.

Lots of practice is about the best I can offer. Be sure you have all your conversion factors memorized and then do a zillion problems until you have 'em down pat.

Do you understand the basics of ratios and working with fractions (multiplication, division, cross-multiplying, canceling, etc)?

Yep...right up until the fractions like I mentioned above get thrown into it. Our instructor provides plenty of practice problems...I just go blank when I see the ones involving the fractions.

suggest you review how to do math with fractions:

• http://www.sweethaven.com/sweethaven...ns/fracs03.asp - fractions
  
• http://www.mathleague.com/help/fractions/fractions.htm#simplifyingcomplexfractions - everything you want to know about factions
  
• http://www.visualfractions.com/ - visual fractions tutorials

http://www.unc.edu/~bangel/quiz/quiz5.htm

Grains are easy if you think of a clock

60mg = gr1 (the 60 is the top of the clock)

15mg= gr 1/4 (15 minutes after the hour)

30mg = gr 1/2 (30 minutes past the hour)

45mg = gr 3/4

etc....

hope that helps

this is why understanding how to work with fractions (multiplying them together) and knowing your conversions in going from systems like apothecary to metric and doing them by dimensional analysis is going to work most efficiently for you. there are links to conversion charts on post #3 of this thread:

• https://allnurses.com/forums/f50/nursing-math-thread-264395.html - the nursing math thread (in the general nursing student discussion forum)

now, here is how you convert 1/150 grain to milligrams:

first, you must know that

1 grain = 65 milligrams

(in some references it is 60 milligrams)

1 grain

(the label "grain" is actually attached to the number 1 in the numerator when setting up the fraction for the equation)

/150

x

65 milligrams/1 grain

(conversion factor) = 0.43333 mg, which you round off to

0.4 mg

.

fyi, this is the typical dose for a tablet of nitroglycerine which is given for chest pain. older doctors will write the order for "grains 1/150" or "1/150 grains"; newer docs will write "0.4 mg". the containers that the nitroglycerine come in are usually labeled with both dosages.

Repetition. Do as many problems as you can and as often as you can. Sister Agnes, my Level II nursing course professor put it best "If you miscalculate a dosage you can kill a patient." and this is why I spent as much time as I could doing calculation problems until I knew it like the back of my hand.

The way my professor taught my class to convert 1/150 grain to milligrams is to replace the 1 with 60 mg and divide 150 into 60.0 which equals 0.4, I find this way to be alot easier. As long as you remember to add the decimal after the 60 you will be okay. I hope this helps.

suggest you review how to do math with fractions:

• http://www.sweethaven.com/sweethaven...ns/fracs03.asp - fractions
  
• http://www.mathleague.com/help/fractions/fractions.htm#simplifyingcomplexfractions - everything you want to know about factions
  
• http://www.visualfractions.com/ - visual fractions tutorials

thanks for the links. the second one shopwed the complex fractions, which is basically what i was talking about.

this is why understanding how to work with fractions (multiplying them together) and knowing your conversions in going from systems like apothecary to metric and doing them by dimensional analysis is going to work most efficiently for you. there are links to conversion charts on post #3 of this thread:

• https://allnurses.com/forums/f50/nursing-math-thread-264395.html - the nursing math thread (in the general nursing student discussion forum)

now, here is how you convert 1/150 grain to milligrams:

first, you must know that

1 grain = 65 milligrams

(in some references it is 60 milligrams)

1 grain

(the label "grain" is actually attached to the number 1 in the numerator when setting up the fraction for the equation)

/150

x

65 milligrams/1 grain

(conversion factor) = 0.43333 mg, which you round off to

0.4 mg

.

fyi, this is the typical dose for a tablet of nitroglycerine which is given for chest pain. older doctors will write the order for "grains 1/150" or "1/150 grains"; newer docs will write "0.4 mg". the containers that the nitroglycerine come in are usually labeled with both dosages.

fabulous!! that's the part i was missing. i was trying to put 1/150 then have a denominator under that.

Fabulous!! That's the part I was missing. I was trying to put 1/150 then have a denominator under that.

Dimensional analysis has been the most important math I have learned in nursing school. I still work out all my problems in this way from start to finish just to be safe.

When it comes to doing ur drug dosages in school (and of course real life) take ur time!! We had to redo our Drug dosage exam (supposedly it was compromised!!!) First exam, this one gal was done in like 5 minutes, wham bam, she was out the door. She pass that 1. BUT since the test was supposedly compromised we ALL had to do it over again! Again, she is wham bam, out the door in 5 minutes (have an hr to do it) she FAILS!!! She passed the rewrite. Point is take ur time and double/triple check ur work, or whatever works best for you. Practice makes perfect!!!

Point is take [your] time and double/triple check [your] work, or whatever works best for you. Practice makes perfect!!!

This can't be stressed enough. I was the only person to ace our dosage exam and the only reason I did was because I went through and double-checked everything and found where I'd made a silly error.

I NEVER walk out of exam rooms early... I may review the test three times and calculate everything two different ways but I always use every minute that they'll give me. Speed counts for nothing; accuracy counts for everything.