HP 20B manual Chain Mode, Algebraic Mode

Mathematical Calculations

Chain Mode

Calculations in Chain mode are interpreted in the order in which they are entered. For example, entering the following numbers and operations as written from left to right 1+2*3=returns 9. See Figure 2.

Figure 2 Calculation in Chain Mode

Note: if you press an operator key, +-*/, after =, the calculation is continued using the currently displayed value.

In Chain mode, if you wish to override the left to right order of entry, use parentheses ()to prioritize operations.

For example, to calculate 1  2  3, you may enter the problem as written from left to right, with parentheses to prioritize the multiplication operation. See Table 2-1 below.

Table 2-1Simple Arithmetic Calculations in Chain Mode

Keys	Display	Description
1+		Sets operational priority, inputs numbers, and
(2*3)		multiplies 2 and 3.
=		Adds 1 to 6 and returns 7.00 on the bottom line as
		the final result.

Algebraic Mode

To set the calculator in Algebraic mode, refer to the section titled, The Mode Menu: Setting Preferences in Chapter 1.

In Algebraic mode, multiplication and division have a higher priority than addition and subtraction. For example, in Algebraic mode, pressing 1+2*3=returns a result of 7.00. In Chain mode, the same key presses return a result of 9.00.

In Algebraic mode, operations between two numbers have the following priority:

Highest priority: the power function (yx)

Second priority: combinations and permutations

Third priority: multiplication and division

Lowest priority: addition and subtraction

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