Question

Express the numbers in scientific notation and state how many significant figures are in the number
1) 0.0020
2) 0.0007
3) 0.000070

Answer 1

You always add a \(\huge 10^{\pm n}\) where \(n\) is the number of times you move the decimal.
For example, if you move the decimal to the \(\sf \color{red}{right}\), \(n\) would be negative. If you move the decimal to the \(\sf \color{blue}{left}\), it would be positive "n".

For all of these, they would be negative "n". The first one is \(\sf 2.0 \times 10^{-3}\)
You always want to keep the correct number of significant figures. In this case, you have two significant figures, so you keep two.

Can you try the other two?