One centimetre on a scale is divided into 20 equal divisions. The least count (minimum value) of this scale is

Options

A. 20 cm
B. 1 mm
C. 0.1 mm
D. 0.5 mm

Explanation

To find the least count of a scale that is divided into equal divisions, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Total Length and Divisions**:
We know that 1 cm on the scale is divided into 20 equal divisions.

2. **Convert the Total Length to Millimeters**:
Since 1 cm is equal to 10 mm, we can express the total length in millimeters:
\[ 1 \text{ cm} = 10 \text{ mm} \]

3. **Calculate the Value of Each Division**:
To find the value of one division, we divide the total length (in mm) by the number of divisions:
\[ \text{Value of each division} = \frac{10 \text{ mm}}{20} = 0.5 \text{ mm} \]

4. **Determine the Least Count**:
The least count of the scale is the value of one division, which we have calculated to be 0.5 mm.

### Final Answer:
The least count of the given scale is **0.5 mm**.

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