The Nursing Math Thread

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A member pm'd me the following question highlighted below. We created this thread for you guys to talk about math, solve math problems, and post math websites that you have found helpful.

I was wondering, is there a sticky or a special site that can be coordinated for "math sufferers". Perhaps, beginning calculations or shall i say the basics..simple to complex...step by step on how to calculate. I'm a visual learner, numbers and I don't work well. I am trying, but I've got a block!

Specializes in OR Pre-op, Post-op.

Should be

20 x 50 =1000

100 x (x) 100

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i have a really dumb question. are you expected to do drug calculations on the spot and in your head? do nurses have a chance to do the calculations on paper and with a calculator? i'm just curious. i have a hard time with math. please give advice.

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Specializes in ALL (as a CNA).

This a GREAT THREAD !

I was wondering where else I was going to get information to review my Nursing Math Skills.

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Specializes in Emergency, Critical Care (CEN, CCRN).
I have a really dumb question. Are you expected to do important drug calculations on the spot and in your head? Do nurses have a chance to do the calculations on paper and with a calculator? I'm just curious. I have a hard time with math. Please give advice.

That depends. If it's an easy calculation (i.e. pt's Rx is for 12.5 mg hydralazine PO BID, drug is supplied as 25 mg tablets, what do you administer), then yes, you can and should be able to do that in your head. However, at least in my hospital and unit, most meds (i.e. IV infusions) that would require "heavy math" such as you're describing, are administered through a pump.

It's always a good idea to be able to do the math as a cross-check against the machine, though. Whether the IV med is pumped or not, you'll still need to be able to figure out the dose, administration time and VTBI (volume to be infused) for the pump, which may or may not be pre-printed or labeled on the bag, and may or may not be correct information relative to the dose, time and VTBI prescribed (!). Basically, the more you can rapidly and accurately cross-check, the better. Practically everyone on my unit keeps a device with a calculator function somewhere on their person (be it an actual calculator, a smartphone, a PDA or whatnot), and every charting computer has a shortcut to MS Calculator on the desktop. If nothing else, you'll need it for end-of-shift I&O totals!

Hope this helps!

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getting ready for some tests in 2-3 weeks, any help with these problems is appreciated!

1. If Sally can paint a house in 4 hours, and John paint the same house in 6 house, how long will it take them to pain the house together???? A – 2hr 24min

2. If 300 jellybeans cost you x dollars, how many jellybeans can you purchase for 50 cents at the same rate???? (I think my answer sheet said answer is 150/x. doesn’t make sense to me)

3. Two cyclists start biking from a trail's start 3 hours apart. The second cyclist travels at 10 miles per hour and starts 3 hours after the first cyclist who is traveling at 6 miles per hour. How much time will pass before the second cyclist catches up with the first from the time the second cyclist started biking??? A – I think its 7.5hrs, any formula?

4. Jim can fill a pool carrying buckets of water in 30 minutes. Sue can do the same job in 45 minutes. Tony can do the same job in 1 ½ hours. How quickly can all three fill the pool together?

5. If Steven can mix 20 drinks in 5 minutes, Sue can mix 20 drinks in 10 minutes, and Jack can mix 20 drinks in 15 minutes, how much time will it take all 3 of them working together to mix the 20 drinks?

6. Sam can do a job in 4 days that Lisa can do in 6 days and Tom can do in 2 days, how long would the job take if Sam, Lisa, and Tom worked together to complete it?

7. If two planes leave the same airport at 1:00 PM, how many miles apart will they be at 3:00 PM if one travels directly north at 150 mph and the other travels directly west at 200 mph? (think book said answer is 500, any forumlua?)

8. How many cubed pieces of fudge that are 3 inches on an edge can be packed into a Christmas tin that is 9 inches deep by 12 inches wide by 8 inches high with the lid still being able to be closed?

9. What will it cost to tile a kitchen floor that is 12 feet wide by 20 feet long if the tile cost $8.91 per square yard?

10. You are lying 120 ft away from a tree that is 50 feet tall. You look up at the top of the tree. Approximately how far is your hear from the top of the tree in a straight line?

11. A cyclist bikes x distance at 10 miles per hour and returns over the same path at 8 miles per hour. What is the cyclist's average rate for the round trip in miles per hour?

12. If edging cost $2.32 per 12-inch stone, and you want a double layer of edging around your flower bed that is 6 yards by 1 yard. How much will edging you flower bed cost?

13. Jonathan can type a 20 page document in 40 minutes, Susan can type it in 30 minutes, and Jack can type it in 24 minutes. Working together, how much time will it take them to type the same document?

14. If the perimeter of a rectangular house is 25 1/3 yards, and the length is 22 feet. What is the width?

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Specializes in med/surg, telemetry, IV therapy, mgmt.
getting ready for some tests in 2-3 weeks, any help with these problems is appreciated!

1. If Sally can paint a house in 4 hours, and John paint the same house in 6 house, how long will it take them to pain the house together???? A - 2hr 24min

2. If 300 jellybeans cost you x dollars, how many jellybeans can you purchase for 50 cents at the same rate???? (I think my answer sheet said answer is 150/x. doesn't make sense to me)

3. Two cyclists start biking from a trail's start 3 hours apart. The second cyclist travels at 10 miles per hour and starts 3 hours after the first cyclist who is traveling at 6 miles per hour. How much time will pass before the second cyclist catches up with the first from the time the second cyclist started biking??? A - I think its 7.5hrs, any formula?

4. Jim can fill a pool carrying buckets of water in 30 minutes. Sue can do the same job in 45 minutes. Tony can do the same job in 1 ½ hours. How quickly can all three fill the pool together?

5. If Steven can mix 20 drinks in 5 minutes, Sue can mix 20 drinks in 10 minutes, and Jack can mix 20 drinks in 15 minutes, how much time will it take all 3 of them working together to mix the 20 drinks?

6. Sam can do a job in 4 days that Lisa can do in 6 days and Tom can do in 2 days, how long would the job take if Sam, Lisa, and Tom worked together to complete it?

7. If two planes leave the same airport at 1:00 PM, how many miles apart will they be at 3:00 PM if one travels directly north at 150 mph and the other travels directly west at 200 mph? (think book said answer is 500, any forumlua?)

8. How many cubed pieces of fudge that are 3 inches on an edge can be packed into a Christmas tin that is 9 inches deep by 12 inches wide by 8 inches high with the lid still being able to be closed?

9. What will it cost to tile a kitchen floor that is 12 feet wide by 20 feet long if the tile cost $8.91 per square yard?

10. You are lying 120 ft away from a tree that is 50 feet tall. You look up at the top of the tree. Approximately how far is your hear from the top of the tree in a straight line?

11. A cyclist bikes x distance at 10 miles per hour and returns over the same path at 8 miles per hour. What is the cyclist's average rate for the round trip in miles per hour?

12. If edging cost $2.32 per 12-inch stone, and you want a double layer of edging around your flower bed that is 6 yards by 1 yard. How much will edging you flower bed cost?

13. Jonathan can type a 20 page document in 40 minutes, Susan can type it in 30 minutes, and Jack can type it in 24 minutes. Working together, how much time will it take them to type the same document?

14. If the perimeter of a rectangular house is 25 1/3 yards, and the length is 22 feet. What is the width?

This is not nursing math. These are algebra word problems. If you search the Internet for instruction on how to solve algebra word problems (there are only about 4 or 5 types represented here) you will find step by step instructions on a number of websites on how to solve these problems.

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Specializes in Primary Care.

I am working on IV Calculations and need help on one question. I think it's missing some information, but not 100% sure on these quite yet. Thanks for all your help and feel free to walk me through figuring these out. I'm most confused about mEq's!!! Any explanations are useful! I understand how to figure out the rate of flow, but it's the MEq's that confusing me! Thank You!

Your pt has an order to infuse 100 ml of D51/2NS with 10 MEq of KCl over the next thirty minutes. The set calibration is 10gtt/ml. What is the correct rate of flow for this pt?

Here's another one:

The order reads: "Over the next 4 hours, infuse 500 ml of 5% Dextrose in Normal Saline. Add 20 MEq of KCl to solution." You know that the IV tubing set is calibrated to deliver 10 gtt/ml. In drops per minute, what is the rate of flow.

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Specializes in Emergency, Critical Care (CEN, CCRN).

In the case of the first question, I would read that as the 10 mEq have already been added, and it's a straight drip-rate calculation: (100 mL x 10 gtt/mL) / 30 min = 33.3 gtt/min.

In the second question, it's a bit trickier, since the question seems to indicate that the D5 didn't come pre-mixed with that 20 mEq. (Usually it does, hence the common report abbreviation "D5 1/2NS +20.") Since you don't know the concentration of the stock solution from which you added your 20 mEq, your final VTBI may be off by a few mL. Nevertheless, it's still a basic drip-rate problem: (VTBI x DF) / TI = DR, where VTBI = volume to be infused, DF = drop factor, TI = time of infusion, and DR = drip rate.

As for the mEq confusing you, all you're doing is adding a medication to an infusing IV; it's just that electrolytes such as potassium are frequently calculated in mEq/L rather than mg/L.

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Specializes in med/surg, telemetry, IV therapy, mgmt.
i am working on iv calculations and need help on one question. i think it's missing some information, but not 100% sure on these quite yet. thanks for all your help and feel free to walk me through figuring these out. i'm most confused about meq's!!! any explanations are useful! i understand how to figure out the rate of flow, but it's the meq's that confusing me! thank you!

your pt has an order to infuse 100 ml of d51/2ns with 10 meq of kcl over the next thirty minutes. the set calibration is 10gtt/ml. what is the correct rate of flow for this pt?

here's another one:

the order reads: "over the next 4 hours, infuse 500 ml of 5% dextrose in normal saline. add 20 meq of kcl to solution." you know that the iv tubing set is calibrated to deliver 10 gtt/ml. in drops per minute, what is the rate of flow.

the meq could be mg or liters. they are not affecting the math to be performed for these problems unless there is an amount in ml for the 10 and 20 meq that the problem assumes you know is added to the iv solution. usually that amount is small (10ml or so). since it doesn't give you that amount i would just work with the main iv solution that the problem gives you. . .

your pt has an order to infuse 100 ml of d51/2ns with 10 meq of kcl over the next thirty minutes. the set calibration is 10gtt/ml. what is the correct rate of flow for this pt?

amount to be infused:
100 ml

time to be infused:
30 minutes

drop factor of iv tubing:
10 gtts/ml

100 ml/30 minutes x 10 gtts/ml = 33.3 gtts/minute, rounded to
33 gtts/min
.

the order reads: "over the next 4 hours, infuse 500 ml of 5% dextrose in normal saline. add 20 meq of kcl to solution." you know that the iv tubing set is calibrated to deliver 10 gtt/ml. in drops per minute, what is the rate of flow.

amount to be infused:
500 ml

time to be infused:
4 hours

conversion factor:
one hour = 60 minutes

drop factor of iv tubing:
10 gtts/ml

500 ml/4 hours x 1 hour/60 minutes (conversion factor) x 10 gtts/ml = 20.8333 gtts/minute, rounded to
21 gtts/min
.

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Specializes in Primary Care.

Murphyle and Daytonite: Thank you very much. Now I know that I basically need to just ignore the added KCl because the amount is so little, that it won't effect the number of gtt too drastically. I just didn't know if I had to add it into the total amount to be infused or not. Now I know not to. Thank you both for your detailed explanations! A lot easier than I had thought!

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Specializes in Primary Care.

Here is another that I am having difficulties since it's sort of "backwards":

1000cc solution of D5NS with 20,000 units of Heparin is infusing at 20ml per hour. The IV set delivers 60 gtts per cc. How many units of Heparin is the pt receiving each hour?

I was figuring that there are 20 units of Heparin per cc (or ml) of D5NS, but how do I figure out the rest? Or do I just multiply the 20 by the gtt, 60, and then divide back with 60 to get the per hour? So, it would be 20 units per hour? Am I doing that correctly?

Thanks.

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the formula for solving this type of problem is: rate per hour x concentration per ml.

to solve the problem: 20 ml/hour x 20 units/ml = 400 units/hour.

i hope this information was helpful. :specs:

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