Math(s) problem - puzzle
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My teacher asked me to write a program on the board and solve it. I wrote:
230 - 220 x 0.5
and announced that the answer was 5! My teacher claimed I was incorrect, but I was not. Can you please explain it to him? Thanks Hint: My teacher was quite embarrassed when I actually said the answer out loud.
Brent
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I think it was meant as a riddle rather than something that actually happened.
Robust Services Core | Software Techniques for Lemmings | Articles
The fox knows many things, but the hedgehog knows one big thing. -
My teacher asked me to write a program on the board and solve it. I wrote:
230 - 220 x 0.5
and announced that the answer was 5! My teacher claimed I was incorrect, but I was not. Can you please explain it to him? Thanks Hint: My teacher was quite embarrassed when I actually said the answer out loud.
Brent
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dbrenth wrote:
Can you please explain it to him?
Dear Teacher, dbrenth is a cocky little so and so, who needs to be taken down a peg or two. ;P
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You teacher was right, and told you the correct result was actually
76. Could you please tell us why?"In testa che avete, Signor di Ceprano?" -- Rigoletto
I thought the answer was 78.
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I thought the answer was 78.
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Sometimes I'm just being a little bit too literal. Daniel's answer above suggests we're both on the same page on this one. :-)
Yeah, you're both on the AR page. :-D
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The fox knows many things, but the hedgehog knows one big thing. -
Octal
Freedom is the freedom to say that two plus two make four. If that is granted, all else follows. -- 6079 Smith W.
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You teacher was right, and told you the correct result was actually
76. Could you please tell us why?"In testa che avete, Signor di Ceprano?" -- Rigoletto
Octal
Freedom is the freedom to say that two plus two make four. If that is granted, all else follows. -- 6079 Smith W.
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You are wrong, the teacher is right. The order of precedence in mathematical operations is (mnemonic PEMDAS): Parentheses Exponentiation Multiplication & Division Addition & Subtraction If two operations have the same precedence, they are evaluated from left to right. Your problem may be rewritten as 230 - (220 x 0.5), the answer to which is obviously not 5.
Freedom is the freedom to say that two plus two make four. If that is granted, all else follows. -- 6079 Smith W.
3! - 1 I think you'll find :) It's curious - nearly everyone I know was taught BODMAS - its the same as PEDMAS, but B=Brackets, O="of". PEDMAS is probably better. Also the great Indian chief "SOH-CAH-TOA". I wonder if they still teach the latter in schools.
KeithBarrow.net[^] - It might not be very good, but at least it is free!
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My teacher asked me to write a program on the board and solve it. I wrote:
230 - 220 x 0.5
and announced that the answer was 5! My teacher claimed I was incorrect, but I was not. Can you please explain it to him? Thanks Hint: My teacher was quite embarrassed when I actually said the answer out loud.
Brent
If you solve it left-to-right, ignoring precedence order, then the answer is 5. An old TI calculator would give you that answer. Today's windows calculator will not: it says 120 because the multiplication is done first.
"They have a consciousness, they have a life, they have a soul! Damn you! Let the rabbits wear glasses! Save our brothers! Can I get an amen?"
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Yeah, you're both on the AR page. :-D
Robust Services Core | Software Techniques for Lemmings | Articles
The fox knows many things, but the hedgehog knows one big thing. -
My teacher asked me to write a program on the board and solve it. I wrote:
230 - 220 x 0.5
and announced that the answer was 5! My teacher claimed I was incorrect, but I was not. Can you please explain it to him? Thanks Hint: My teacher was quite embarrassed when I actually said the answer out loud.
Brent
And today you learn that nobody likes a smartarse ... :laugh:
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony "Common sense is so rare these days, it should be classified as a super power" - Random T-shirt AntiTwitter: @DalekDave is now a follower!
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And today you learn that nobody likes a smartarse ... :laugh:
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony "Common sense is so rare these days, it should be classified as a super power" - Random T-shirt AntiTwitter: @DalekDave is now a follower!
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My teacher asked me to write a program on the board and solve it. I wrote:
230 - 220 x 0.5
and announced that the answer was 5! My teacher claimed I was incorrect, but I was not. Can you please explain it to him? Thanks Hint: My teacher was quite embarrassed when I actually said the answer out loud.
Brent
Very clever :thumbsup:
cheers Chris Maunder
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3! - 1 I think you'll find :) It's curious - nearly everyone I know was taught BODMAS - its the same as PEDMAS, but B=Brackets, O="of". PEDMAS is probably better. Also the great Indian chief "SOH-CAH-TOA". I wonder if they still teach the latter in schools.
KeithBarrow.net[^] - It might not be very good, but at least it is free!
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My teacher asked me to write a program on the board and solve it. I wrote:
230 - 220 x 0.5
and announced that the answer was 5! My teacher claimed I was incorrect, but I was not. Can you please explain it to him? Thanks Hint: My teacher was quite embarrassed when I actually said the answer out loud.
Brent
The teacher was not embarrassed but shocked that any student could be so wrong. The division MUST be carried out before the subtraction. 230 – 220 × 0.5 = 230 – 110 = 120. Try it in any scientific calculator or programming language. You are alone (I hope) in thinking the answer is 5. Are you perhaps joking?
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You are wrong, the teacher is right. The order of precedence in mathematical operations is (mnemonic PEMDAS): Parentheses Exponentiation Multiplication & Division Addition & Subtraction If two operations have the same precedence, they are evaluated from left to right. Your problem may be rewritten as 230 - (220 x 0.5), the answer to which is obviously not 5.
Freedom is the freedom to say that two plus two make four. If that is granted, all else follows. -- 6079 Smith W.
You write "the answer to which is obviously not 5". Nobody ever said that. The OP sais that he "announced that the answer was 5!". Do you see the difference? The exclamation mark. The answer is 5! (five factorial) and 5!=5*4*3*2*1=120 so 5! is the correct answer :-)
