Chemistry significant figures problem?

The reason is the 210. Although in addition significant figures only apply to the decimals, when a number with no given decimals is given, you will take the regular significant figures from that digit and use it. 210 has 2 sig. figs. 12.5 + 10.20 + 210 = 232.7, but we must reduce to 2 sig. figs, which is 230. Hope that helped.