For your viewing and studying pleasure, today's post is an excerpt from my Master Tutor Project. Enjoy.
This is an idea I got from my high school chemistry
teacher for remembering placement of the decimal in significant figures. It is called the Atlantic and
Pacific rule.
Most people will recognize that the “P” acific Ocean is on
the left, while the “A” tlantic Ocean is on the right. If a decimal is “P” resent count all
non-zeros starting at the left. If a
decimal is “A” bsent count all non-zeros starting at the right. Any bodies of water between the Atlantic and
Pacific are ignored, just as any zeros in the middle of a number are
ignored. (Image Source: http://www.theodora.com/maps/new3/north_america_color.gif). Examples:
503,000
Note that a decimal point is absent.
Therefore, start on the right count all non-zeros e.g. 503 thus 3
significant figures. But, 503,000.00 has
a decimal point present, so start at the Pacific or the left side or 8
significant figures. But 0.001 has only 1 because the first three zeros are
non-significant.
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