When multiplying, the number of significant figures in the answer should be the same as the number of significant figures in the original number with the least number of sig. figs., in this case 2 sig. figs. because 2.1 has 2 and 2.336 has 4 sig. figs.
2.1 x 2.336 = 4.9056
Rounding to 2 significant figures = 4.9