Dosage calculation question

Editorial Team / Admin · Aug 2, 2005

okay here's what im converting
gr 1/120=_____mg
I know there's 60mg in one gr but the fraction throws me off. How do i work this out. HELP!!!
Do i write out 1/120 as a decimal?
maybe a stupid question

Go to http://www.goatconnection.com/articles/publish/printer

There are other sites that have problem solving, too.

Good luck!!

Siri, CRNP, CLNC, RLNC

mhull · Aug 2, 2005

okay here's what im converting
gr 1/120=_____mg
I know there's 60mg in one gr but the fraction throws me off. How do i work this out. HELP!!!
Do i write out 1/120 as a decimal?
maybe a stupid question

I think I am doing this right...

I converted 1/120gr to 0.0083gr

0.0083gr = 1gr

-------- ----

X mg = 60mg

X = 0.498mg

My school would have wanted it rounded to 0.5mg

Hope that helps, and it looks right to me. You will have to put the spaces in on the conversion, it won't allow me to post it like i wanted it.

MIA-RN1, RN · Aug 2, 2005

okay here's what im converting
gr 1/120=_____mg
I know there's 60mg in one gr but the fraction throws me off. How do i work this out. HELP!!!
Do i write out 1/120 as a decimal?
maybe a stupid question

not stupid. I hate fractions.

this from my 17 year old who helps me with math:

one gram over 1 = 60 mg over 1

You want to find how many mg in 1/120gr

so multiply both sides by 1/120

so you get 1/120gr = 60/120mg which equal 0.5 or 1/2

Not quite sure how he did that.

Editorial Team / Admin · Aug 2, 2005

Yes, you are correct.

That website I gave you is down. Try:

http://www.dmacc.cc.ia.us/medmath1/apothecary/apoth.html

The above is a good site for problems.

Weight

20 grains 1 scruple

3 scruples 1 dram

8 drams 1 ounce

3 scruples 60 grains (gr)

1 ounce 480 gr

1 pound 5,760 gr

Volume

1 fluid dram 60 minims (m)

8 fluid dram 1 fluid ounces (fl.oz)

1 fl. oz 480 m = 8 fl. drams

1 pint (pt) 7680 m = 16 fl. oz

1 quart(qt) 2 pt.

1 gallon 4 qt

Approximate equivalents of milligrams (mg) and grains (gr)

0.2 mg 1/300 gr

0.3 mg 1/200 gr

0.4 mg 1/150 gr

0.5 mg 1/120 gr

1 mg 1/60 gr

3 mg 1/20 gr

6 mg 1/10 gr

10 mg 1/6 gr

15 mg 1/4 gr

25 mg 3/8 gr

30 mg 1/2 gr

60 mg 1 gr

120 mg 2 gr

200 mg 3 gr

300 mg 5 gr

500 mg 7 1/2 gr

600 mg 10 gr

1000 mg 15 gr

Approximate equivalents of grams (gm) and grains (gr)

0.0002 gm 1/300 gr

0.0003 gm 1/200 gr

0.0004 gm 1/150 gr

0.0005 gm 1/120 gr

0.0006 gm 1/100 gr

0.001 gm 1/60 gr

0.01 gm 1/6 gr

0.015 gm 1/4 gr

0.025 gm 3/8 gr

0.03 gm 1/2 gr

0.06 gm 1 gr

0.12 gm 2 gr

0.2 gm 3 gr

0.3 gm 5 gr

0.5 gm 7.5 gr

0.6 gm 10 gr

1 gm 15 gr

Good luck!!!

Siri

Nurseismade RN · Aug 2, 2005

okay here's what im converting
gr 1/120=_____mg
I know there's 60mg in one gr but the fraction throws me off. How do i work this out. HELP!!!
Do i write out 1/120 as a decimal?
maybe a stupid question

Hi ready,

I just started studying dosage calculations, so forgive me if it is wrong.

since you know that 60mg = 1 gr. I used this format:-

1/120=x/60

cross multiply and you get 60=120x

divide both sides by 120

which then looks like 60/120=120x/120

which is .5=x

ans .5mg