how would I do this problem.."perform the operation and express the answer using the correct # of significant.

Question

figures? It's physics, and the problem is 42.3 x 2.61
when I multiply it out, it is 110.403
I have to round that number so that there are only 3 significant figures. When I rounded to 110, there are only 2 significant figures, and when I round it to 110.4, there are 4 significant figures. Please help!

Answer 1

No...110 has three significant figures. The number itself, can have 2 or 3 significant figures, but in this context it has 3.

This can be indicated with a decimal, but no following zero: 110.

Answer 2

110.4 would have 4 sig. figs.
110.0 would also have 4 sig. figs.
110 has 3 sig. figs.