Answer:
Four significant figures
Step-by-step explanation:
Rules of significant figure:
1. Zeros before any non-zero digit are considered to be NON-significant.
2. Any zeros between any non-zero digits are SIGNIFICANT
0.505
Here, there are three significant digits: 505
3. Any zeros that are to the right of the decimal point and a non-zero number are SIGNIFICANT.
4.0000
4. All non - zero digit are significant
Therefore,
0.002040 has four significant figures
2040
