{"id":1139,"date":"2012-12-20T20:55:46","date_gmt":"2012-12-20T20:55:46","guid":{"rendered":"http:\/\/www.oracletutoring.ca\/blog\/?p=1139"},"modified":"2012-12-20T20:55:46","modified_gmt":"2012-12-20T20:55:46","slug":"significant-figures-adding-and-subtracting","status":"publish","type":"post","link":"https:\/\/www.oracletutoring.ca\/blog\/significant-figures-adding-and-subtracting\/","title":{"rendered":"Significant Figures: Adding and Subtracting"},"content":{"rendered":"

We continue our commentary on significant figures – aka significant digits – with how\u00a0to add and subtract them.\u00a0 A\u00a0chemistry or physics tutor deals with this topic periodically.<\/h1>\n

If you look over my last few posts, you’ll see the accumulation of\u00a0articles on significant digits.\u00a0 Today, we cover\u00a0adding and subtracting, which is a bit trickier than multiplying and dividing.<\/p>\n

With adding or subtracting, you need to see<\/em> the numbers arranged in a column to understand what to do.<\/p>\n

Take, for example, 54.28-49.329.<\/p>\n

Step 1:\u00a0 Write the calculation in a column.
\n\"\"
\nStep 2:\u00a0 Notice the last place on the right where both numbers have a digit.\u00a0 Draw a cut-off line there.
\n\"\"<\/p>\n

Step 3:\u00a0 Realize that any figures to the right of the cutoff are not<\/em> significant.\u00a0 This is why, in the case above, the answer is 4.95 in significant figures.<\/p>\n

While 54.28 has four significant digits and 49.329 has five, the answer has only three.\u00a0 Significant figures can be destroyed by subtraction, whereas they can’t be by multiplication or division.\u00a0 (See the previous post to understand why.)<\/p>\n

Here’s another example:\u00a0 adding this time.<\/p>\n

6.26 + 9.1<\/p>\n

Here’s our result:
\n\"\"
\nNote that, because the next digit is greater than 5, we round up, giving 15.4.<\/p>\n

As we’ve seen, subtraction can destroy significant figures.\u00a0 Can addition create them?\u00a0 See for yourself:
\n\"\"<\/p>\n

Apparently, each addend has only two sigificant digits, while the answer has three.\u00a0 Some professors may raise their eyebrows at this:)<\/p>\n

Jack of Oracle Tutoring by Jack and Diane<\/a>, Campbell River, BC.<\/p>\n","protected":false},"excerpt":{"rendered":"

We continue our commentary on significant figures – aka significant digits – with how\u00a0to add and subtract them.\u00a0 A\u00a0chemistry or physics tutor deals with this topic periodically. If you look over my last few posts, you’ll see the accumulation of\u00a0articles …<\/p>\n

Significant Figures: Adding and Subtracting<\/span> Read More »<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[11,7,10],"tags":[],"class_list":["post-1139","post","type-post","status-publish","format-standard","hentry","category-chemistry","category-physics","category-sciences"],"_links":{"self":[{"href":"https:\/\/www.oracletutoring.ca\/blog\/wp-json\/wp\/v2\/posts\/1139","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.oracletutoring.ca\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.oracletutoring.ca\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.oracletutoring.ca\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.oracletutoring.ca\/blog\/wp-json\/wp\/v2\/comments?post=1139"}],"version-history":[{"count":26,"href":"https:\/\/www.oracletutoring.ca\/blog\/wp-json\/wp\/v2\/posts\/1139\/revisions"}],"predecessor-version":[{"id":1165,"href":"https:\/\/www.oracletutoring.ca\/blog\/wp-json\/wp\/v2\/posts\/1139\/revisions\/1165"}],"wp:attachment":[{"href":"https:\/\/www.oracletutoring.ca\/blog\/wp-json\/wp\/v2\/media?parent=1139"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.oracletutoring.ca\/blog\/wp-json\/wp\/v2\/categories?post=1139"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.oracletutoring.ca\/blog\/wp-json\/wp\/v2\/tags?post=1139"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}