Write 23.578 to 3 significant figures. Count from the first non-zero digit. The next digit decides whether that figure rounds up. Zeros at the start do not count. For a named column, such as the nearest tenth, use round to a place.
Write 23.578 to 3 significant figures.
Use 1 to 6. A 5 rounds up. If the rounded number ends in placeholder zeros, the working also shows standard form so the figures stay visible.