charsibb Posted March 6, 2015 Group: Member Topic Count: 653 Content Count: 31,049 Reputation: 2,487 Days Won: 172 Joined: 08/30/2011 Share Posted March 6, 2015 Have heard the quote before, but never heard the explanation. Pretty interesting! The statement is, "2 + 2 = 5 for very large values of 2." It's a joke about rounding and estimating. For instance, suppose you have your calculator set to round all numbers to integers (no decimal places) and the problem you're actually computing is 2.48 + 2.47. The calculator will automatically round, so when you punch 2.48 and ENTER, it will show up on the screen as 2. When you punch in the 2.47 and ENTER, it will also show up on the screen as 2. Then when you add, the sum 4.95 will be rounded to 5. Hence, 2 + 2 = 5 if the value of 2 is large enough. It's a joke ... but a joke with a somewhat serious point. All measurements in the real world (as opposed to the esoteric whirled of mathematics) are estimates; they're always rounded to something. There's no such thing as absolute precision. So rounding must come into play sometime or other, and the joke about 2 + 2 = 5 if 2 is large enough, is a reminder about the way that estimation errors compound. http://www.straightdope.com/columns/read/1382/does-2-2-5-for-very-large-values-of-2 Link to comment Share on other sites More sharing options...
raptorcj Posted March 6, 2015 Group: Member Topic Count: 18 Content Count: 8,878 Reputation: 1,266 Days Won: 28 Joined: 07/12/2013 Share Posted March 6, 2015 So I guess that means 2 x 2 = 6. I love this math, would be entertaining to teach after the kids have their times tables down! Link to comment Share on other sites More sharing options...
charsibb Posted March 6, 2015 Group: Member Topic Count: 653 Content Count: 31,049 Reputation: 2,487 Days Won: 172 Joined: 08/30/2011 Author Share Posted March 6, 2015 So I guess that means 2 x 2 = 6. I love this math, would be entertaining to teach after the kids have their times tables down! You are correct, sir! Same data, different format, cut and pasted from XL. Ain't math wunnerful!!?!? 2.45 + 2.47 = 4.92 2.45 x 2.47 = 6.0515 2 + 2 = 5 2 x 2 = 6 Link to comment Share on other sites More sharing options...
Apis Bull Posted March 6, 2015 Group: Member Topic Count: 1,586 Content Count: 23,185 Reputation: 2,332 Days Won: 65 Joined: 09/05/2002 Share Posted March 6, 2015 So I guess that means 2 x 2 = 6. I love this math, would be entertaining to teach after the kids have their times tables down! You are correct, sir! Same data, different format, cut and pasted from XL. Ain't math wunnerful!!?!? 2.45 + 2.47 = 4.92 2.45 x 2.47 = 6.0515 2 + 2 = 5 2 x 2 = 6 The thing is, when you're actually doing math, if you determine that you're using one significant figure, then that's what you multiply. You wouldn't write 2 and then use 2.45. Link to comment Share on other sites More sharing options...
charsibb Posted March 6, 2015 Group: Member Topic Count: 653 Content Count: 31,049 Reputation: 2,487 Days Won: 172 Joined: 08/30/2011 Author Share Posted March 6, 2015 So I guess that means 2 x 2 = 6. I love this math, would be entertaining to teach after the kids have their times tables down! You are correct, sir! Same data, different format, cut and pasted from XL. Ain't math wunnerful!!?!? 2.45 + 2.47 = 4.92 2.45 x 2.47 = 6.0515 2 + 2 = 5 2 x 2 = 6 The thing is, when you're actually doing math, if you determine that you're using one significant figure, then that's what you multiply. You wouldn't write 2 and then use 2.45. LOL Link to comment Share on other sites More sharing options...
Leviathan Posted March 7, 2015 Group: Member Topic Count: 83 Content Count: 1,720 Reputation: 207 Days Won: 3 Joined: 02/11/2011 Share Posted March 7, 2015 Link to comment Share on other sites More sharing options...
DELdaBull Posted March 30, 2015 Group: Member Topic Count: 86 Content Count: 17,061 Reputation: 1,429 Days Won: 19 Joined: 09/15/2005 Share Posted March 30, 2015 So I guess that means 2 x 2 = 6. I love this math, would be entertaining to teach after the kids have their times tables down! You are correct, sir! Same data, different format, cut and pasted from XL. Ain't math wunnerful!!?!? 2.45 + 2.47 = 4.92 2.45 x 2.47 = 6.0515 2 + 2 = 5 2 x 2 = 6 But it should be 2.48 and not 2.45 Link to comment Share on other sites More sharing options...
Gismo Posted April 21, 2015 Group: Member Topic Count: 417 Content Count: 9,680 Reputation: 1,233 Days Won: 8 Joined: 09/24/2009 Share Posted April 21, 2015 Speaking of rounding.... In Colorado they have a highway sign that reads "mile 419.99" ... Because the sign that read 420 kept getting stolen, presumably by pot heads. Link to comment Share on other sites More sharing options...
charsibb Posted April 21, 2015 Group: Member Topic Count: 653 Content Count: 31,049 Reputation: 2,487 Days Won: 172 Joined: 08/30/2011 Author Share Posted April 21, 2015 Speaking of rounding.... In Colorado they have a highway sign that reads "mile 419.99" ... Because the sign that read 420 kept getting stolen, presumably by pot heads. Now that's funny! I didn't realize yesterday was 4/20 until I was testing the projection equipment sound last night and brought up youtube and just clicked the first video link without looking at it. My students were VERY amused to see cops smoking pot in the classroom. Oops! Link to comment Share on other sites More sharing options...
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