What does Please Excuse My Dear Aunt Sally mean?
Parenthesis, Exponents, Multiplication Division, Add Subtract.
"Please Excuse My Dear Aunt Sally" is a commonly used mnemonic or memory aid in mathematics. It helps students remember the correct sequence of operations (order of operations) when solving arithmetic expressions.
Each letter in the sentence represents a different mathematical operation, and the order in which they should be performed:
P - Parentheses (perform operations within parentheses first)
E - Exponents (perform exponentiation)
M - Multiplication (perform multiplication)
D - Division (perform division)
A - Addition (perform addition)
S - Subtraction (perform subtraction)
So, when solving an arithmetic expression, you should first perform any operations within parentheses, then handle any exponents, followed by multiplication and division from left to right, and finally, perform addition and subtraction from left to right.
For example, in the expression 6 ÷ 2(1 + 2), you would first simplify the expression inside the parentheses: 1 + 2 = 3. Then, using the order of operations, you would perform the division: 6 ÷ 2 = 3. Finally, you would perform the multiplication: 3 × 3 = 9.
"Please Excuse My Dear Aunt Sally" serves as a helpful reminder to follow the correct order of operations and avoid any ambiguity in arithmetic expressions.