How To Pass HESI A2 Mathematics

This section of the HESI A2 exam will test you on your ability to understand proportions and ratios, rate, and military time. Below are some of the key concepts you will need to understand in order to do well in this section.

Order of Operations mean things like add, subtract, multiply, divide, squaring, etc. Use PEMDAS to remember the order in which basic operations must be performed in an algebraic expression. PEMDAS (remembered by many by using the mnemonic “Please Excuse My Dear Aunt Sally”) stands for Parentheses, Exponents, Multiplication and/or Division (in the order in which they first appear), and Addition and Subtraction (also in the order in which they first appear).

1. Parentheses: Parentheses are used to indicate the operations that should be done first. For example, in 4 – (2 + 1) = 1; the parentheses show us that we must first add 2 and 1, before subtracting the sum from 4 (instead of subtracting 2 from 4 and then adding 1 (this would give us an incorrect answer of 3).

    

2. Exponents: Exponents are superscript numbers placed at the top right of another number. They show how many times the base number is multiplied by itself. Exponents provide a shorter way of writing a longer mathematical expression. Example: 𝑎² = 𝑎 × 𝑎; 2⁴ = 2 × 2 × 2 × 2.

    

3. Multiplication and/or Division: both of these operations have the same priority and the way to know which one you’ll complete first, simply do the one that occurs first (going left to right).
4. Addition and/or Subtraction: The same situation here as above. Both addition and subtraction have equal priority but which one you’ll perform first is based on which one comes first (left to right).

Rational Number Word Problems: Operations are presented in “word” problems using the following terms:

• “more than” = addition
• “of” = multiplication
• “by how much” and “increased” = going from smaller to larger amounts (can be found by subtracting)
• “decreased”: indicated the difference between two numbers, amounts, etc.
• “is” and “are” indicate = equivalence

So, if we look at the statement: 40% of doctors are emergency room doctors, we can translate “of” to multiplication and “are” to equals. If we know that 20 doctors work in the emergency room, we can determine the total number of doctors by writing the problem as this mathematical sentence:

40% X n = 20. Then convert 40% = .4 so: .4n = 20. Dividing each side by .4, we can determine that there are 50 doctors in total. 

Remember: percentage means “per hundred.” Percentages are like fractions based on a whole of 100. The fraction that most easily converts to a percentage has 100 as the denominator.

Inequalities: the following symbols are used to express inequalities

• = means “equals”
• > means “is greater than” or “is more than”
• ≥ means ” is greater than is least or “no less than”
• < means ” is less than” or “is fewer than”
• ≤ means ” is less than or is at most or “no more than”

   

Measurement Conversions – Key concepts

• Equivalent amount – When converting larger to smaller units, multiply the known amount by the equivalent amount. If the reverse is the case, divide.
• Conversion fractions: The conversion factor has the known amount; the other has the unknown amounts. Multiply the two to get the converted measurement.
• Conversion Units: U.S. and Metric Equivalents, Metric Conversions, Capacity Measurements, Weight Measurements, Nursing Measurements