Round off 0.07284 to four, three and two significant digits.

Explanation

To round off the number 0.07284 to four, three, and two significant digits, we will follow a systematic approach. Here’s the step-by-step solution:

### Step 1: Identify Significant Digits
The number given is 0.07284. When considering significant digits, leading zeros (the zeros before the first non-zero digit) do not count. Therefore, the significant digits start from the first non-zero digit, which is 7 in this case.

### Step 2: Round Off to Four Significant Digits
1. The first four significant digits in 0.07284 are 7, 2, 8, and 4.
2. Since we are rounding to four significant digits, we take these digits as they are.
3. Thus, rounding off 0.07284 to four significant digits gives us **0.07284**.

### Step 3: Round Off to Three Significant Digits
1. The first three significant digits are 7, 2, and 8.
2. The next digit after 8 is 4, which is less than 5.
3. Therefore, we do not round up the last digit (8).
4. Thus, rounding off 0.07284 to three significant digits gives us **0.0728**.

### Step 4: Round Off to Two Significant Digits
1. The first two significant digits are 7 and 2.
2. The next digits after 2 are 8 and 4, which together form the number 84.
3. Since 84 is greater than 50, we round up the last significant digit (2) to 3.
4. Thus, rounding off 0.07284 to two significant digits gives us **0.073**.

### Summary of Results
- Rounded to 4 significant digits: **0.07284**
- Rounded to 3 significant digits: **0.0728**
- Rounded to 2 significant digits: **0.073**

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