# How many significant figures are in the number 5400?

Dec 6, 2015

I am assuming that $5400$ is $5400$ as-written.

As such, $5400$ is relevant to the following rules for significant figures:

PROMINENT DEFINITIONS

• All nonzero digits are significant.
• A trailing zero goes after a decimal point, or after all nonzero digits, or both, and no nonzero digits follow it.

SPECIAL CONDITIONS

• All "placeholder" zeroes AFTER a nonzero digit but BEFORE an implicit or explicit decimal point are subject to the following conditions:
• If an explicit decimal point is specified, they are significant if and only if a nonzero digit precedes them.
• If no explicit decimal point is specified, they are NOT significant.

Therefore, there are TWO significant figures (not four).