Decimal division to find the missing numerator Solve for x in: x / 0.0025 = 800.

Introduction / Context: This question checks comfort with decimal division and isolating an unknown in a basic equation. Recognizing 0.0025 as 25/10000 (or 1/400) can simplify the mental math significantly.

Given Data / Assumptions:

• x / 0.0025 = 800.
• All values are exact decimals.
• No rounding is needed.

Concept / Approach: Multiply both sides by 0.0025 to isolate x: x = 800 * 0.0025. Then evaluate the product using fraction equivalents or straightforward multiplication.

Step-by-Step Solution:x / 0.0025 = 800 ⇒ x = 800 * 0.0025.Note 0.0025 = 25/10000 = 1/400.So x = 800 * (1/400) = 800 / 400 = 2.

Verification / Alternative check: Check by substitution: 2 / 0.0025 = 2 / (1/400) = 800. Correct.

Why Other Options Are Wrong:.2 or .02: These are too small; dividing them by 0.0025 gives 80 or 8, not 800.2000: Far too large; 2000 / 0.0025 would be 800000.

Common Pitfalls: Treating 0.0025 as 1/40 instead of 1/400, or forgetting to multiply both sides by the divisor. Converting to a simple fraction helps avoid errors.

Final Answer: 2