by using decimals
686.88 rounded to 3 significant digits is 687
1.239 rounded to 3 significant digits is 1.24
It is: 2.360
It is 4730.
5.60
2.56
Rounded to the nearest tenth, there can be only one decimal. And that is 7.8
2.641, 2.642, 2.643, 2.644
There are five significant digits.
100 (rounded up to the nearest 200).
150