Napa Valley College
Associate Degree Program in Nursing   

Math Calculation Practice Questions

  1. You have an order to give Penicillin 150,000 Units (I.M.). You have a vial of Penicillin containing 3,000,000 Units in 10ml. How many ml. will you give?_____________

  2. The doctor orders Demerol 25 mg. (I.M.) q4h prn. You have Demerol 100mg. in 2ml. How many ml will you give? _________________

  3. Your patient is to receive Digoxin 0.125 mg. On hand you have Digoxin 500 mcg in 2 ml. How many ml will you give? ________________

  4. The drug order reads ASA gr.X q4h prn. for headache. You have ASA 325 mg tablets. How many tablets will you give? __________________

  5. The doctor’s order reads: Phenobarbital gr. ss (1/2) q6h. You have Phenobarbital 15 mg tablets. How many tablets will you give? _________ 

  6. In question #5, how many tablets will you give in 24 hours? _________ 

  7. The doctor orders Atropine gr. 1/200 I.M. stat. You have a vial that reads: Atropine gr. 1/150 in 2ml. How many ml will you give?  ____________ 

  8. Your patient is to receive Atropine 0.3 mg. You have Atropine 1/150 gr. in 1 ml. How many ml will you give?______________

  9. The order reads: Valium 15 mg p.o. T.I.D. The label reads: Valium gr. ½. How many tablets would you give in a 24-hour period?  ____________ 

  10. The doctor orders Streptomycin 400mg. The vial label reads Streptomycin 1 Gm in 2.5ml. How many ml will you give? ________________

  11. You are to give 240 ml of osmolyte through a feeding tube over a three hour period. The drop factor for the solution set is 15. How many drops per minute will you give?____________

  12. The doctor orders Klonopin 1mg daily for a child who weighs 36 pounds. Calculate the safe range for this medication based on 0.01 - 0.05mg/kg/day. ___________________

  13. Will you give the child the dose ordered in question 12? ___yes _____no

 


Math Calculation Practice Answers & Tips

Remember, for all math calculations:  

v     Label each part of your calculation to stay on track

v     If you are working with different units of measurements, you need to convert to equivalent measures  

v     Read the question carefully. Is it asking for a single dose, total dose in 24 hours, dose based on weight, or safe range of a dose?  

v     Use correct interpretation of abbreviations – examples:  BID , bid =twice a day, q6h = every six hours, prn = whenever necessary  

1.         You have an order to give Penicillin 150,000U (I.M.). You have a vial of Penicillin containing 3,000,000Units in 10ml. How many ml will you give?   0.5ml

            Three ways to set up problem:

            a.         X ml :150,000Units = 10 ml : 3,000,000Units

            b.         3,000,000 U  =  150,000 U 
                                10 ml                X ml 

            c.         150,000 U  x  10 ml        Dose Desired   x  Volume
                       3,000,000 U                    Dose on hand                       

2.                The doctor orders Demerol 25mg. (I.M.) q4h prn. You have Demerol 100mg. in 2ml. How many ml will you give?  0.5ml

a.         X ml : 25mg = 2ml : 100mg 

b.         100 mg  =  25 mg
                2 ml         X ml 

c.         25mg x 2 ml
            100 mg

 

3.                 Your patient is to receive Digoxin 0.125 mg. On hand you have Digoxin 500mcg in 2 cc’s. How many cc’s will you give?  0.5 cc

First convert mcg to mg.  500mcg = 0.5mg

Then set up problem as above.  

 

4.                 The drug order reads ASA gr.X  q4h prn. for headache. You have ASA 325 mg tablets. How many tablets will you give?   2 tablets

First convert grains to mg.  60 mg = 1gr. therefore  10grains = 600mg.

X tab : 600mg =  1 tab : 325mg  

After setting up and solving problem the result will be 1.8 tablets. You will give two tablets – remember that converting from  METRIC SYSTEM TO AN APOTHECARY SYSTEM FREQUENTLY RESULTS IN EQUIVALENTS AND NOT EQUALS.  You will learn that many standard doses are accepted as the norms for equivalency.

 

5.                The doctor’s order reads: Phenobarbital gr. ss  (1/2)  q6h. You have Phenobarbital 15 mg tablets. How many tablets will you give?   2 tablets

First convert grains to mg.  1/2gr x 60 = 30mg  

 

6.                In question #5, how many tablets will you give in 24 hours?  8 tablets

Q6h = 4 times a day spaced at 6 hour intervals  (24 hours  = 4 doses)
                                                                                                    
6 hour

4 doses x 2 tablets each dose = 8 tablets  

 

7.                 The doctor orders Atropine gr. 1/200 stat. You have a vial that reads: Atropine gr. 1/150 in 2cc. How many ml’s will you give?   1.5ml.

           (Tests ability to multiply and divide fractions)

8.                 Your patient is to receive Atropine 0.3 mg. You have Atropine 1/150 gr. in 1 ml. How many ml’s will you give?  0.75ml

First convert grains to mg.  60 x 1/150  = 0.4 mg    1/150 gr = 0.4 mg     

 

9.                 The order reads: Valium 15 mg p.o. T.I.D. The label reads: Valium gr. ½. How many tablets would you give in a 24-hour period?  1 ½ tablets

            First convert grains to mg  ½ x 60 = 30 mg.

You will give ½ tablet three times in 24 hours.  ½ x 3 = 1 ½  

 

10.              The doctor orders Streptomycin 400mg. The vial label reads Streptomycin 1 Gm in 2.5 ml. How many ml will you give?   1 cc

            First convert Gm to mg. 1Gm = 1000mg.

 

11.      You are to give 240 cc of osmolyte through a feeding tube over a three hour period. The drop factor for the solution set is 15. How many drops per minute will you give?  20gtts/minute

Formula  = volume in one hour x gtt factor
                               
60 minutes                              

First calculate how many ml in one hour = 80ml

80 ml x 15(gtt factor)    = 20 gtts/minute
   
60 minutes      

      

12.     The doctor orders Klonopin 1 mg daily for a child who weighs 36 pounds. Calculate the  safe range for this medication based on a safe range of 0.01 – 0.05mg/kg/day. 

First calculate the child's weight in kilograms (kg). Divide 36 lb by 2.2 kg = 16.36 kg

Multiply the child’s weight in kg by the lowest and highest safe dose.

The safe range is 0.01mg/16.36kg/day ( 0.01 x 16.36 = 0.16mg) to 0.05mg/16.36kg/day (0.05 x 16.36 = 0.82mg).  

 

13.             Will you give the child the dose ordered?  No

No because 1.00 mg exceeds the highest safe dose of 0.82 mg.

                                  


Conversion Methods

Visualize the difference between milligrams, grains, and Grams

Weights

Metric

 

Apothecary

 

Metric

         

1 milligram (1 mg )

 

1/60 grain (gr)

 

0.001 Gram (0.001Gm)

         

60 milligrams (60 mg)

 

1 grain (1 gr)

 

0.06 Gram (0.06Gm)

         

1000 mg

 

15 gr

 

1 Gm

         

1000 micrograms (mcg) =

1 mg

   

0.001 Gm

         

Grams to grains = multiply by 15

Grains to Grams = divide by 15

Grains to milligrams = multiply by 60

milligrams to grains = divide by 60

Grams to milligrams = move decimal point three places to the right

milligrams to Grams = move decimal point three places to left

micrograms to milligrams = move decimal point three places to left

Volumes

1.0 milliliter (ml or cc)

 

15 minims (m)

 

15 drops (gtts)

         

5.0 ml (cc)

 

1 dram

 

1 tsp.

         

30 ml (cc)

 

1 ounce (oz)

 

8 tsp. = 2 T

         

500 ml (cc)

 

1 pint (pt.)

 

2 cups

         

1000 ml (cc) = 1 liter (L)

 

1 quart (qt)

 

4 cups

         

Weight 2.2 pounds ( lb ) = 1 kilogram (kg)

kg to pounds = kg x 2.2      lb to kg = lb ÷ 2.2

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