Order of operation is a useful concept not only in math but also in real life. The operators include parentheses, exponents, multiplication, division, addition, and subtraction (Panasuk, 2022). The illustrative example can be the following: John has a salary of 1000$, he pays 60% of it for his rent, and 1/10 of his salary goes for child support; he spends 200$ on food each month. If John spares all the money left each month, how long will it take to save 1000$? To solve this real-life situation, one should write the expression: 1000/(1000-1000*0,6-1000*1/10-200) equals 10. It means that John can save 1000$ in 10 months with such a salary and expenditures each month. To solve this expression, the expression in parentheses should be calculated, and more specifically, firstly multiplication and division, and only then subtraction. Afterward, the division by the result obtained in parentheses should be performed. If the order is not followed, and, for instance, the division inside the parentheses will be calculated first, the expression loses its sense as the solution will be negative.
In the post, an example from the healthcare field is provided. As my peer writes, in case of giving a medication for stroke, it is essential to calculate the correct dose to a patient to avoid any undesirable consequences. As intravenous r-TPA (0.9 mg/kg, maximum 90 mg) with 10% of the amount given as a bolus followed by the rest as an infusion over 60 minutes, the dose should be calculated with regard to a patient’s weight. The following expression is given in the post: if the weight is 110 lbs., then 110/2.2 x 0.9 = 45 mg should be given. According to the order of operations, they are followed from left to right; in other case, a result would be wrong, and overdose happens (55.6 mg). Another way to avoid confusion, in this case, is to use parentheses (110/2.2) x 0.9 = 45 mg. Therefore, order of operations is necessary even to save people’s lives and cure them. Are there any other medications that require more complex calculations? And is it always right to use weight-based dosing? It appears to be confusing sometimes as it implies the standardization of weight estimation.
Reference
Panasuk, R. (2022). Order of Operations: Connecting to Real Life and Algebra. Illinois Mathematics Teacher, 57(1), 32-37.