Step 1: Identify the number of decimal places

The decimal 4.2 has 1 decimal places.

Step 2: Multiply by the appropriate power of 10

Multiply by 10¹ = 10 to eliminate the decimal point.

4.2 × 10 = 42

Step 3: Write as a fraction

Step 4: Simplify the fraction

Find the greatest common divisor (GCD) of 42 and 10.

GCD(42, 10) = 2

Divide both the numerator and denominator by the GCD: