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The words `+`

, `-`

, `*`

, `/`

, and `mod`

always
operate on the top two stack items:

2 2 .s + .s . 2 1 - . 7 3 mod .

The operands of `-`

, `/`

, and `mod`

are in the same order
as in the corresponding infix expression (this is generally the case in
Forth).

Parentheses are superfluous (and not available), because the order of the words unambiguously determines the order of evaluation and the operands:

3 4 + 5 * . 3 4 5 * + .

Assignment:What are the infix expressions corresponding to the Forth code above? Write`6-7*8+9`

in Forth notation^{1}.

To change the sign, use `negate`

:

2 negate .

Assignment:Convert -(-3)*4-5 to Forth.

`/mod`

performs both `/`

and `mod`

.

7 3 /mod . .

Reference: Arithmetic.