Bill and Bob entered "3 + 2 * 4" into their calculators.  TOPIC_SOLVED

Topics that don't fit anywhere else.

Bill and Bob entered "3 + 2 * 4" into their calculators.

Postby maggiemagnet on Fri Apr 17, 2009 4:16 pm

Bill and Bob entered the expression "3 + 2 * 4" into their calculators. Bill got "20" for the answer, while Bob got "11".

The instructor concluded that Bob had a scientific calculator, but that Bill had a simpler model. How did the instructor know this? (Hint: What did Bob's calculator do differently from Bill's?)


I've punched this into my son's calculator and into the calculator that's on my cell phone, and they do give the two different answers. But the displays look a lot alike, and I'm pushing the same buttons in the same order. What am I missing? :confused:

Thank you!
User avatar
maggiemagnet
 
Posts: 297
Joined: Mon Dec 08, 2008 12:32 am

Sponsor

Sponsor
 

Re: Bill and Bob entered "3 + 2 * 4" into their calculators.

Postby Martingale on Fri Apr 17, 2009 4:49 pm

maggiemagnet wrote:Bill and Bob entered the expression "3 + 2 * 4" into their calculators. Bill got "20" for the answer, while Bob got "11".

The instructor concluded that Bob had a scientific calculator, but that Bill had a simpler model. How did the instructor know this? (Hint: What did Bob's calculator do differently from Bill's?)


I've punched this into my son's calculator and into the calculator that's on my cell phone, and they do give the two different answers. But the displays look a lot alike, and I'm pushing the same buttons in the same order. What am I missing? :confused:

Thank you!


the correct answer is 11.


the answer of 20 will only come from old calculators/or crappy calculators

then you put in 3+2 the calculator adds them right then and then when you hit *4 the calculator is actually computing

(3+2)*4=5*4=20
User avatar
Martingale
 
Posts: 363
Joined: Mon Mar 30, 2009 1:30 pm
Location: USA

Postby maggiemagnet on Fri Apr 17, 2009 11:47 pm

So this is an order-of-operations thing, with the el-cheapo not being able to "understand" it? (That makes sense, but I'd appreciate confirmation or, if I'm off-track, redirection.)

Thank you.
User avatar
maggiemagnet
 
Posts: 297
Joined: Mon Dec 08, 2008 12:32 am

Re:  TOPIC_SOLVED

Postby Martingale on Sat Apr 18, 2009 12:32 am

maggiemagnet wrote:So this is an order-of-operations thing, with the el-cheapo not being able to "understand" it? (That makes sense, but I'd appreciate confirmation or, if I'm off-track, redirection.)

Thank you.


you are correct. The 'bad' calc is not considering order of operations. It computes things as they are entered with little to no regard to the operations being performed.
User avatar
Martingale
 
Posts: 363
Joined: Mon Mar 30, 2009 1:30 pm
Location: USA

Re: Bill and Bob entered "3 + 2 * 4" into their calculators.

Postby maggiemagnet on Sat Apr 18, 2009 2:03 pm

Thank you very much! :clap:
User avatar
maggiemagnet
 
Posts: 297
Joined: Mon Dec 08, 2008 12:32 am


Return to Uncategorized