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  1. Estimation 180 - Andrew Stadel
    A new estimation challenge every day of the school year, with accompanying video answers. Join the number sense challenge online by submitting your own estimates, explaining your reasoning ("What context clues did you use?") and rating your accuracy ("How confident are you?"). more>>

    "The calculator that thinks only if you think, too," QAMA requires the operator to first enter a reasonable estimate. QAMA encourages rounding and rapid back-of-the-envelope reckoning, but does not tolerate errors of magnitude or sign, or of basic operations with single digits. Read user instructions, scope, and more. QAMA derives from "Quick Approximate Mental Arithmetic," but also happens to mean “How Much?" in Hebrew. more>>

  3. A View from the Back of the Envelope - Mitchell N. Charity
    Pages about approximation. Counting by powers of ten includes the "what order of magnitude is ...?" game, illustrated instructions for counting to ten billion on your fingers, and lots of dots -- a million dots on one page, and a dot for every second in the day, with a real-time count-down graphic. The section on scaling the universe provides ways to visualize how big things are using analogies and examples, covering nanometers (nm), micrometers (um), millimeters (mm), meters (m), kilometers (km), megameters (Mm), gigameters (Gm), terameters (Tm), and petameters (Pm). How to simplify a number by rounding, rounding to an order of magnitude, sliding the decimal point, and using a number you can remember; this section also offers some calculations comparing the volume and surface area of a sphere and a box. Exponential notation discusses sliding the decimal point, order of magnitude and rounding to it, and scientific notation and how to write and speak it. Fermi questions examine rough quantitative estimates about the world: the "What order of magnitude is ...?" game, a Pinocchio estimation game, an order of magnitude investigation into the emulsification power of raw eggs in the making of mayonnaise, reflections on Why be approximate? and On Being Approximate, and a few notes on landmarks, bounding, and honesty. The scale of some things: people, people-seconds, volume, area, length, time, mass, energy, area, the ratio surface volume-to-density, speed, volume rate (how fast volume flows, shifts, accumulates, or drains), and power. The section on developing "deep" understanding addresses brevity as a measure of comprehension, and getting a feel for big numbers, with examples on picturing altitude above maps, teleportation, probing near space with a flashlight, and atomic bonding. Body ruler measuring covers length with your body: measuring angle and distance with your thumb. Additional resources include the 1957 book Cosmic View: The Universe in 40 Jumps laid out on web pages. more>>


Mason error

component stack:   /library/branch.html
code stack:   /var/lib/mason/obj/library/branch.html:208

debug info:   Debug file is '/var/lib/mason/debug/anon/13'.


raw error:

error while executing /library/branch.html:
Server message number=1105 severity=17 state=1 line=1 text=Can't allocate space for object 'keystorage' in database 'catalog' because 'default' segment is full/has no free extents. If you ran out of space in syslogs, dump the transaction log. Otherwise, use ALTER DATABASE or sp_extendsegment to increase size of the segment.
Statement=INSERT INTO keystorage ( keys ) VALUES ( '6888;64210;7256;8553;75212;75403;3380;63054;76463;62156;77234;7264;60679;75850;41533;65424;6066;8590;8602;8500;8591;9072;6031;6929;5508;11215;6216;7045;6162;3242;8369;8575;8554;10386;63814;8726;8497;12113;8734...
Server message number=7101 severity=17 state=1 line=1 text=Unable to allocate new text value, dbid 6.
Statement=INSERT INTO keystorage ( keys ) VALUES ( '6888;64210;7256;8553;75212;75403;3380;63054;76463;62156;77234;7264;60679;75850;41533;65424;6066;8590;8602;8500;8591;9072;6031;6929;5508;11215;6216;7045;6162;3242;8369;8575;8554;10386;63814;8726;8497;12113;8734...
HTML::Mason::Interp::__ANON__('Server message number=1105 severity=17 state=1 line=1 text=Can\'...') called at /usr/lib/perl5/site_perl/5.6.0/Forum/Key.pm line 284
Forum::Key::store('Forum::Key=HASH(0x8f88d98)') called at /var/lib/mason/obj/library/branch.html line 208
HTML::Mason::Commands::__ANON__('passed_args', 'HASH(0x8f82ebc)', 'tree', 'topics', 'branch', 'estimation') called at /usr/lib/perl5/site_perl/5.6.0/HTML/Mason/Component.pm line 131
HTML::Mason::Component::run('HTML::Mason::Component::FileBased=HASH(0x8f7bfc0)', 'passed_args', 'HASH(0x8f82ebc)', 'tree', 'topics', 'branch', 'estimation') called at /usr/lib/perl5/site_perl/5.6.0/HTML/Mason/Request.pm line 653
require 0 called at /usr/lib/perl5/site_perl/5.6.0/HTML/Mason/Request.pm line 653
HTML::Mason::Request::comp('HTML::Mason::Request::ApacheHandler=HASH(0x8e68334)', '/library/branch.html', 'passed_args', 'HASH(0x8f82ebc)', 'tree', 'topics', 'branch', 'estimation') called at /usr/lib/perl5/site_perl/5.6.0/HTML/Mason/Commands.pm line 70
HTML::Mason::Commands::mc_comp('/library/branch.html', 'passed_args', 'HASH(0x8f82ebc)', 'tree', 'topics', 'branch', 'estimation') called at /var/lib/mason/obj/library/dhandler line 90
HTML::Mason::Commands::__ANON__('start_at', 1, 'num_to_see', 50, 'keyid', 39387506) called at /usr/lib/perl5/site_perl/5.6.0/HTML/Mason/Component.pm line 131
HTML::Mason::Component::run('HTML::Mason::Component::FileBased=HASH(0x8f85d30)', 'start_at', 1, 'num_to_see', 50, 'keyid', 39387506) called at /usr/lib/perl5/site_perl/5.6.0/HTML/Mason/Request.pm line 653
require 0 called at /usr/lib/perl5/site_perl/5.6.0/HTML/Mason/Request.pm line 653
HTML::Mason::Request::comp('HTML::Mason::Request::ApacheHandler=HASH(0x8e68334)', 1, 'HTML::Mason::Request::ApacheHandler=HASH(0x8e68334)', 'HASH(0x8e724a4)', 'HTML::Mason::Component::FileBased=HASH(0x8f85d30)', 'start_at', 1, 'num_to_see', ...) called at /usr/lib/perl5/site_perl/5.6.0/HTML/Mason/Request.pm line 159
require 0 called at /usr/lib/perl5/site_perl/5.6.0/HTML/Mason/Request.pm line 159
HTML::Mason::Request::exec('HTML::Mason::Request::ApacheHandler=HASH(0x8e68334)', '/library/topics/estimation', 'start_at', 1, 'num_to_see', 50, 'keyid', 39387506) called at /usr/lib/perl5/site_perl/5.6.0/HTML/Mason/ApacheHandler.pm line 914
HTML::Mason::ApacheHandler::handle_request_1('HTML::Mason::ApacheHandler=HASH(0x8de2afc)', 'Apache=SCALAR(0x8e5f99c)', 'HTML::Mason::Request::ApacheHandler=HASH(0x8e68334)', 'HASH(0x8e1a728)') called at /usr/lib/perl5/site_perl/5.6.0/HTML/Mason/ApacheHandler.pm line 560
require 0 called at /usr/lib/perl5/site_perl/5.6.0/HTML/Mason/ApacheHandler.pm line 560
HTML::Mason::ApacheHandler::handle_request('HTML::Mason::ApacheHandler=HASH(0x8de2afc)', 'Apache=SCALAR(0x8e5f99c)') called at /etc/httpd/conf/handler.pl line 97
HTML::Mason::handler('Apache=SCALAR(0x8e5f99c)') called at /dev/null line 0
require 0 called at /dev/null line 0