Subject: General Aptitude · Chapter: Number System · Exam: · Marks: · Difficulty:
The numbers 1, 2, 3, 4, 1000 are multiplied together. The number of zeros at the end (on the right) of the product must be
(a)30
(b)200
(c)211
(d)249
Answer
Answer (as printed): D
Explanation
Let $N=1 \times 2 \times 3 \times 4 \times \ldots \ldots \ldots \times 1000=1000$ ! Clearly, the highest power of 2 in $N$ is very high as compared to that of 5. So, the number of zeros in $N$ will be equal to the highest power of 5 in $N$. ∴ Required number of zeros $$\begin{aligned} & =\left[\frac{1000}{5}\right]+\left[\frac{1000}{5^{2}}\right]+\left[\frac{1000}{5^{3}}\right]+\left[\frac{1000}{5^{4}}\right] \\ & =200+40+8+1=249 . \end{aligned}$$
Explanation as extracted from the printed page; notation may be imperfect.