甚麼是 Significant Figures ?

Significant figures
Significant figures is the number of digits between the first leftmost non-zero digit and last digit.
For example,
123472(6 sig. .fig)
23.478(5 sig. fig.)
0.1099(4 sig. fig.)
0.000079900(5 sig. fig.)
Rounding off(四捨五入)
31465 = 31470(corr. to the nearest ten OR 4 sig. fig.)
31465 = 31500(corr. to the nearest hundred OR 3 sig. fig.)
31465=31000(corr. to the nearest thousand OR 2 sig. fig.)
31465=30000(corr. to the nearest ten thousand OR 1 sig. fig.)
14.932 = 14.93 (corr. to the nearest hundredth OR corr. to 2 decimal places(d.p.) OR 4 sig. fig.)
37.5695 = 37.570 (corr. to the nearest thousandth OR corr. to 3 d.p. OR 5 sig. fig.)
38.6 = 39 (corr. to the nearest integer)
0.003716 = 0.00372 (corr. to 5 d.p. OR 3 sig. fig.)
2.371 x 10-8=2.4 x 10-8 (corr. to 2 sig.fig.)
Round Off 3.63414 Correct To Three Significant Figures :
3.63414=3.63 (Correct To Three Significant Figures)

即係有效數字~
如你既題目要round off to 3 個有效數字~
答案係3.63
明未?