Step 1: Identify the number of decimal places

The decimal 0.4 has 1 decimal places.

Step 2: Multiply by the appropriate power of 10

Multiply by 10¹ = 10 to eliminate the decimal point.

0.4 × 10 = 4

Step 3: Write as a fraction

Step 4: Simplify the fraction

Find the greatest common divisor (GCD) of 4 and 10.

GCD(4, 10) = 2

Divide both the numerator and denominator by the GCD: