How do I turn 128.576 joules into 2 sig figs

Question

DrBob222 · Accepted Answer

Here is the link. Hope it helps https://www.chemteam.info/SigFigs/SigFigs.html

DrBob222 · Answer

1.29E2

DrBob222 · Answer

oops I did 3 s.f. To 2 it is 1.3E2.

Josh · Answer

What’s E2 mean I’m so confused

DrBob222 · Answer

1.2E2 means 1.2 x 10^2 or in other words it is 1.2 x 100. You can round 128.576 to 128.58 (5 s.f.); 128.6(4 s.f.); 128 (3 s.f.) but we have problem if we try to do less than 3 BECAUSE if we try 2 places we write 12.0 but that has 3 s.f., or 12 but we can't put another digit there without getting 3 so we write 1.2 x 10^2. That tells us it has 2 s.f. but the decimal point is two places to the right. There is a very good discussion of s.f. by the chem team. I will post a link.