In order to convert 20 cm to inches, we need to use the conversion factor between centimeters and inches. One inch is equal to 2.54 centimeters, so we can use this factor to convert 20 cm to inches.

The formula for converting centimeters to inches is:

**Inches = Centimeters ÷ 2.54**

Using this formula, we can plug in 20 for centimeters and get:

Inches = 20 cm ÷ 2.54

Now we just need to simplify this expression and solve for inches. We can do this by dividing 20 by 2.54 using a calculator or by long division. Here’s the calculation:

Inches = 20 ÷ 2.54 Inches = 7.874

Therefore, 20 cm is equivalent to 7.874 inches (rounded to three decimal places).

To check our work, we can also use the reverse conversion formula to convert 7.874 inches back to centimeters and see if we get 20 cm. The formula for converting inches to centimeters is:

Centimeters = Inches × 2.54

Using this formula, we can plug in 7.874 for inches and get:

Centimeters = 7.874 in × 2.54 Centimeters = 20.00596

So, we get 20.00596 cm which is very close to our original value of 20 cm. The slight difference is due to rounding error.

**In summary, to convert 20 cm to inches:**

- Use the conversion factor: 1 inch = 2.54 cm
- Divide 20 cm by 2.54 to get the equivalent in inches
- Simplify the expression and solve for inches
- The result is 7.874 inches (rounded to three decimal places)

It is important to note that when converting between different units of measurement, it is important to use the correct conversion factor and to be consistent with units throughout the calculation. This will ensure accurate and reliable results.