An army lost 10% of its men in war. 10% of the remaining died due to disease and 10% of the rest were declared disabled. Thus the strength of the army was reduced to 729000 active men. The original strength of the army was :

Answer: Option B

Initial number of soldiers in the army = x
According to the question,
$$\begin{array}{rl}& \Rightarrow \text{x}\times \frac{90}{100}\times \frac{90}{100}\times \frac{90}{100}=729000\\ & \Rightarrow x=\frac{729000\times 1000}{9\times 9\times 9}\\ & \Rightarrow x=1000000\end{array}$$

---

Alternate:
10% → $$\frac{1}{10}$$
10 → 9 in war
10 → 9 in disease
10 → 9 disabled
100 → 729
729 → 729000
1 → 1000
10000 → 1000 × 1000 = 1000000