A [b]significant figure[/b] (or [b]SF[/b]) is the first [b]non-zero number[/b].
After the first [b]SF[/b] all figures are taken into account (are significant).
Round up or down on the final SF.
Add zeroes at the end for decimals, if the SF needs you to.
[h3]Examples[/h3]
[ol]
[li]1.0070638 = 1.007 (4sf)[/li]
[li]70.638 = 71 (2sf)[/li]
[li]706.38 = 700 (1sf)[/li]
[li]0.0070638 = 0.007064 (4sf)[/li]
[li]70638 = 70600 (3sf)[/li]
[li]5037 [divide] 8 = 629.6 (3sf)[/li]
[li]21.38 [divide] 0.3 = 71.3 (3sf)[/li]
[b]You should assume that an answer requires 3SF if it has 2 or more decimal places.[/b]
