User Manual

Chapter 1: Operating the TI-84 Plus Silver Edition 29

Equation Operating System (EOS™)

Order of Evaluation

The Equation Operating System (EOS™) defines the order in which functions in expressions are

entered and evaluated on the TI-84 Plus. EOS™ lets you enter numbers and functions in a simple,

straightforward sequence.

EOS™ evaluates the functions in an expression in this order.

Note: Within a priority level, EOS™ evaluates functions from left to right. Calculations within

parentheses are evaluated first.

Implied Multiplication

The TI-84 Plus recognizes implied multiplication, so you need not press ¯ to express

multiplication in all cases. For example, the TI-84 Plus interprets

2p, 4sin(46), 5(1+2), and (2…5)7 as

implied multiplication.

Note: TI-84 Plus implied multiplication rules, although like the TI-83, differ from those of the TI-82.

For example, the TI-84 Plus evaluates

1à2X as (1à2)…X, while the TI-82 evaluates 1à2X as 1à(2…X)

(Chapter

2).

Parentheses

All calculations inside a pair of parentheses are completed first. For example, in the expression

4(1+2), EOS first evaluates the portion inside the parentheses, 1+2, and then multiplies the answer,

3, by 4.

Order Number Function

Functions that precede the argument, such as

‡, sin(, or log(

Functions that are entered after the argument, such as

, !, ¡,

, and

conversions

Powers and roots, such as 2

4 Permutations (nPr) and combinations (nCr)

5 Multiplication, implied multiplication, and division

6 Addition and subtraction

Relational functions, such as > or 

8 Logic operator and

9 Logic operators or and xor