A string is wound around a pencil 20 times and the total thickness of the turns is found to be 2 cm and 5 mm. What is the thickness of the string?

Answer

To find the thickness of the string wound around the pencil, we can follow these steps:

### Step 1: Identify the given values
- Number of turns (n) = 20
- Total thickness of the turns = 2 cm and 5 mm

### Step 2: Convert the total thickness into a single unit
We need to convert the total thickness from centimeters and millimeters to just millimeters for easier calculation.
- 2 cm = 20 mm (since 1 cm = 10 mm)
- Therefore, total thickness = 20 mm + 5 mm = 25 mm

### Step 3: Calculate the thickness of the string
To find the thickness of the string, we divide the total thickness by the number of turns:
- Thickness of the string (t) = Total thickness / Number of turns
- t = 25 mm / 20

### Step 4: Perform the division
Now, we calculate:
- t = 25 mm / 20 = 1.25 mm

### Conclusion
The thickness of the string is **1.25 mm**.

---