What is a Keystroke Sequence?Date: 07/30/2002 at 13:33:35 From: Charice Subject: Keystroke sequence What is a 'keystroke sequence'? It is used in the following question: Write out the keystroke sequence required to calculate 8/[3^4-(-4-3)]. My husband is doing a math placement exercise, and neither of us is sure how to begin solving this problem. Thanks! Date: 07/30/2002 at 18:02:51 From: Doctor Ian Subject: Re: Keystroke sequence Hi Charice, A keystroke sequence is the sequence of keys that you would punch on a particular calculator to find the value of some expression. Note that for a given expression, the proper keystroke sequence will differ from calculator to calculator. Think of it this way. Suppose you're on the phone with someone who has a calculator, and you want him to work out the value of an expression for you, but he doesn't understand math at all. You have to tell him what keys to press, in what order, e.g., to compute 3/(2 + 4) you'd have to say something like this: Press '2' Press '+' Press '4' Press '=' Press 'STO' (store this result) Press '3' Press '/' Press 'RCL' (recall the previously stored result) Press '=' Tell me what you see. In this case, the keystroke sequence would be '2', '+', '4', '=', 'STO', '3', '/', 'RCL', '=' On a different calculator (one with parentheses), it might be '3', '/', '(', '2', '+', '4', ')', '=' On a calculator that uses Reverse Polish Notation, the keystroke sequence would be '3', '2', '4', '+', '/' (In this case, the '/' says "Of the two most recent operands, divide the first by the second"; but when the second operand turns out to be an operator, the '+' says "Of the two most recent operands, add the first to the second." When that operation is done, it becomes the second operand for the first operation. If this doesn't make sense to you, make sure not to buy this kind of calculator!) Does this help? - Doctor Ian, The Math Forum http://mathforum.org/dr.math/ |
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