Step 1: Identify the number of decimal places

The decimal 1.288399 has 6 decimal places.

Step 2: Multiply by the appropriate power of 10

Multiply by 10⁶ = 1000000 to eliminate the decimal point.

1.288399 × 1000000 = 1288399

Step 3: Write as a fraction

Step 4: Simplify the fraction

Find the greatest common divisor (GCD) of 1288399 and 1000000.

GCD(1288399, 1000000) = 1

Divide both the numerator and denominator by the GCD: