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TS EAMCET · Maths · Binomial Theorem

Let \(n=1 !+4 !+7 !+\ldots+400 !\). Then ten's digit of \(n\) is

  1. A 1
  2. B 6
  3. C 2
  4. D 7
Verified Solution

Answer & Solution

Correct Answer

(B) 6

Step-by-step Solution

Detailed explanation

Given, \(n=1 !+4 !+7 !+\ldots+400 !\) \(1 !=1,4 !=24,7 !=5040,10 !=3628800\) and further the terms has last two digits \(=00\) So, \(1 !+4 !+7 !+\ldots+400 !=\ldots \ldots 65\) Here ten digit is 6 . Hence, 6 is the answer.