IV Compounding Math Question: How is a Tic Tac Toe Board Used In This Example?

by Sherri
(Raleigh NC USA)

An order for 6 liters of 0.9% soium chloride solution is to be prepared from 23.4% concentrated NaCl solution and sterile water for injection.How many mL of each will be used?

The answer is supposed to be 231 mL of 23.4% and 5769 mL of water but I can't seem to figure out how they got their answer or what formula they used. What is the tic tac toe board supposed to look like? Do I multiply by 6, 6000, or 1000? or do i do the usual cross multiply and divide with the 1000?

Comments for IV Compounding Math Question: How is a Tic Tac Toe Board Used In This Example?

Average Rating starstarstarstarstar

Click here to add your own comments

Tic Tac Toe Board and Answer...
by: Robert

This Pharmacy IV Math question can be solved by using the Tic Tac Toe Board. Using the amounts supplied, the board would be set up as follows:

Middle square – 0.9

Top left square – 23.4

Bottom left square – 0

Following the instructions, subtract the amount in the middle square from the top left square – 23.4% - 0.9% = 22.5% - and this amount goes in the bottom right square. Do the same thing with the middle left and bottom left square – 0.9% - 0 = 0.9% and put this amount in the top right square. Next add the top right and bottom right numbers – 22.5 + 0.9 = 23.4. The answers are then multiplied by the volume needed, which is 6 liters or 6000 milliliters.. 6000 multiplied by 0.9 divided by 23.4 equals 231 ml of concentrated NACL. 6000 – 231 = 5769 ml of sterile water.

Here is an example of how to set up a Tic Tac Toe Board to aid in finding the answer to solution preparation.

Use a regular Tic Tac Toe Board that you can simply draw on a piece of paper. In the middle square of the board write the desired strength. In the top left square, place the higher strength solution. In the bottom left square, place the lower strength unless you are using water in which case this number would be a zero.

Subtract the amount in the middle square from the amount in the top left square. Put this number in the bottom right square, then subtract the amount in the middle square from the bottom left square and put this amount in the top right square.

Add the numbers in the top and bottom right squares and divide the top right number and the bottom right number by this amount. Multiply each answer by the volume needed and the result will be how much is needed of each solution. To make certain it is the right answer, add the two and it should be equal to the total volume.

You will find the majority of the time the Tic Tac Toe Board will help you to find the right solution. Because practicality dictates that it is easier to dilute than to compound preparations, alligation is the method used for solving these problems when mixing different strength products. Using a Tic Tac Toe Board for the process is one of the simplest ways of doing so.

I hope this solution will help you.
by: Anonymous

1. 23.4%-0.9% = 22.5%
2. 0.9%-0=. 0.9%

Total quantity you get is 0.9+22.5= 23.4
So 6000ml of 0.9 is 6000*0.9\23.4= 231 ml
231ml is concentrated NACL solution. To find out sterile water we subtract
6000ml - 231 ml= 5769 ml sterile water.

Click here to add your own comments

Join in and write your own page! It's easy to do. How? Simply click here to return to Pharmacy Tech Math Questions.

Back to Home

[?]Subscribe To This Site
  • follow us in feedly
  • Add to My Yahoo!

Didn't find what you were looking for? Use the box below to search this entire site.

Custom Search

Recent Articles

  1. 250mg/5mL Dispense 200mL Sig: 5mL q.i.d

    Dec 06, 17 11:16 PM

    How do you set this up to solve to find the days supply?

    Read More

  2. Days Supply Question: Neurontin 300mg 1 tablet po every other day #15

    Nov 27, 17 11:39 PM

    Neurontin 300 mg tablets #15 1 tab po qod What is the days supply?

    Read More

  3. Days Supply Question - Take One Tablet by Mouth Every 4 Hours As Needed for Pain Not To Exceed 6 Per Day

    Nov 27, 17 11:25 PM

    Take One Tablet by Mouth Every 4 Hours As Needed for Pain Not To Exceed 6 Per Day

    Read More

  4. Pharmacy Technician Cover Letters

    Nov 18, 17 07:44 PM

    Pharmacy Technician Cover Letters - The basic format to use when writing your Cover Letter, as well as what to write to make sure your resume gets moved into the "interview" pile.

    Read More

  5. Days Supply Question - #20 pills, 1.5 tablets by mouth daily

    Nov 18, 17 06:16 PM

    If you have 20 pills and you take 1.5 a days what's the days supply

    Read More

  6. Days Supply/Quantity for Stavudine (Zerit) prescription

    Nov 18, 17 06:05 PM

    Your pharmacy stocks stavudine in bottles of 30 capsules. How many capsules would you need to dispense for a 90 day supply?

    Read More

  7. Hospital Pharmacy Technician

    Nov 18, 17 02:17 AM

    Duties and Responsibilities of the Hospital Pharmacy Technician.

    Read More

  8. The Metric System for Pharmacy Technicians

    Nov 18, 17 01:20 AM

    This page discusses how Pharmacy Technicians use the Metric System of Measurement.

    Read More

  9. What is the days supply on Advair 250/50 #1 1 puff q12h?

    Nov 04, 17 10:37 PM

    What is the days supply on advair 250/50 #1 - 1 puff q12h?

    Read More

  10. Pharmacy Root Cause Analysis

    Oct 29, 17 10:40 PM

    Pharmacy Root Cause Analysis (RCA) - What is an RCA? How can it help PharmTechs and Save Lives?

    Read More

  11. Controlled Substance Pharmacy Technician

    Oct 29, 17 10:12 PM

    Controlled Substance Pharmacy Technician - Responsibilities, Qualifications, A Day in the Life, and Work Advantages

    Read More

  12. IV Infusion Calculations Explained

    Oct 29, 17 09:54 PM

    This page explains IV Infusion Calculations you may use in your job as a Pharmacy Technician.

    Read More

  13. Days Supply Question: Norco, #35 pills, 1 tablet every 4-6 hours

    Oct 29, 17 09:41 PM

    How many days should 35 Norco last me if I was given #35 at 1 every 4-6 hours?

    Read More

  14. Improving Pharmacy Safety Culture

    Oct 27, 17 08:01 PM

    This page discusses ways of Improving Pharmacy Safety Culture - Focusing on Work Environment, Processes and Procedures, not Personnel

    Read More

  15. How much dextrose is in D10W in a 250 bag?

    Oct 15, 17 04:54 PM

    In D10W, how much dextrose is in a 250mL bag?

    Read More