{"id":180,"date":"2006-10-09T20:57:48","date_gmt":"2006-10-09T20:57:48","guid":{"rendered":"http:\/\/scientopia.org\/blogs\/goodmath\/2006\/10\/09\/no-abacus-handy-use-your-hands\/"},"modified":"2006-10-09T20:57:48","modified_gmt":"2006-10-09T20:57:48","slug":"no-abacus-handy-use-your-hands","status":"publish","type":"post","link":"http:\/\/www.goodmath.org\/blog\/2006\/10\/09\/no-abacus-handy-use-your-hands\/","title":{"rendered":"No Abacus Handy? Use your hands."},"content":{"rendered":"<p>Suppose you want to do some math, but you don&#8217;t have an abacus handy. Oh, the horror! What do you do?<br \/>\nNo problem! Your hands make a *great* two-digit soroban-type abacus. The four beads on the lower deck are your four fingers; the bead on the upper deck is your thumb, as illustrated in this diagram (with apologies for my terrible artwork):<br \/>\n<img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" alt=\"hand-abacus.jpg\" src=\"https:\/\/i0.wp.com\/scientopia.org\/img-archive\/goodmath\/img_81.jpg?resize=394%2C181\" width=\"394\" height=\"181\" \/><br \/>\nSo the numbers from one to nine look like:<br \/>\n<img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" alt=\"finger-numbers.jpg\" src=\"https:\/\/i0.wp.com\/scientopia.org\/img-archive\/goodmath\/img_82.jpg?resize=280%2C360\" width=\"280\" height=\"360\" \/><br \/>\nTo get two digits, you use your right hand for the ones, and your left for the tens. So, for example, let&#8217;s look at a simple addition:<br \/>\n<img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" alt=\"finger-add.jpg\" src=\"https:\/\/i0.wp.com\/scientopia.org\/img-archive\/goodmath\/img_83.jpg?resize=317%2C447\" width=\"317\" height=\"447\" \/><br \/>\nOnce you know the abacus, doing this with your hands is pretty simple. It&#8217;s definitely a limited technique, since you can&#8217;t get past one hundred without using your toes, but it&#8217;s a nifty trick, and it&#8217;s easy to teach kids to do this for working out math problems. If you&#8217;ve got a kid who&#8217;s a tactile thinker, it&#8217;s amazing how much learning to do this can help them. I&#8217;ve seen kids who do paper math with many digits by working out subparts of the problem using this style of finger-abacus.<br \/>\nThere&#8217;s actually a whole Korean teaching method for math called something like chisan-bop. From what I understand, they build up on this quite a bit, to be able to do much more complicated stuff than just two-digit addition, but I haven&#8217;t been able to find an english textbook on chisan-bop. All the english texts basically show what I just did above: the two-digit abacus on the fingers.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Suppose you want to do some math, but you don&#8217;t have an abacus handy. Oh, the horror! What do you do? No problem! Your hands make a *great* two-digit soroban-type abacus. The four beads on the lower deck are your four fingers; the bead on the upper deck is your thumb, as illustrated in this [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[34],"tags":[],"class_list":["post-180","post","type-post","status-publish","format-standard","hentry","category-manual-computing-devices"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/p4lzZS-2U","jetpack_sharing_enabled":true,"jetpack_likes_enabled":true,"_links":{"self":[{"href":"http:\/\/www.goodmath.org\/blog\/wp-json\/wp\/v2\/posts\/180","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.goodmath.org\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.goodmath.org\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.goodmath.org\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.goodmath.org\/blog\/wp-json\/wp\/v2\/comments?post=180"}],"version-history":[{"count":0,"href":"http:\/\/www.goodmath.org\/blog\/wp-json\/wp\/v2\/posts\/180\/revisions"}],"wp:attachment":[{"href":"http:\/\/www.goodmath.org\/blog\/wp-json\/wp\/v2\/media?parent=180"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.goodmath.org\/blog\/wp-json\/wp\/v2\/categories?post=180"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.goodmath.org\/blog\/wp-json\/wp\/v2\/tags?post=180"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}