The number of significant figures in 0.00210 is

Options

A. five
B. six
C. four
D. three

Answer

To determine the number of significant figures in the number 0.00210, we can follow these steps:

### Step 1: Identify the digits in the number
The number given is 0.00210. We can break it down into its individual digits:
- The digits are: 0, 0, 2, 1, 0.

### Step 2: Recognize leading zeros
Leading zeros are the zeros that appear before the first non-zero digit. In this case, the leading zeros are the first two zeros (0.00). These leading zeros are not counted as significant figures.

### Step 3: Identify non-zero digits
The non-zero digits in the number are:
- 2 and 1.

### Step 4: Identify trailing zeros
Trailing zeros are zeros that come after a non-zero digit in a decimal number. In this case, the last zero (0) after the digit 1 is a trailing zero. Trailing zeros in a decimal number are counted as significant figures.

### Step 5: Count the significant figures
Now, we can count the significant figures:
- Non-zero digits: 2 (1 significant figure) and 1 (1 significant figure).
- Trailing zero: 0 (1 significant figure).

So, we have:
- 2 (1 significant figure)
- 1 (1 significant figure)
- 0 (1 significant figure)

Total significant figures = 1 (from 2) + 1 (from 1) + 1 (from trailing zero) = 3 significant figures.

### Conclusion
Thus, the number of significant figures in 0.00210 is **3**.

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