Permutations And Combinations Question 318

Question: How many numbers with no more than three digits can be formed using only the digits 1 through 7 with no digit used more than once in a given number?

Options:

A) 259

B) 249

C) 257

D) 252

Show Answer

Answer:

Correct Answer: A

Solution:

  • [a] (i) Number of 3 digit nos. $ =7\times 6\times 5=210 $ (ii) Number of 2 digit nos. $ =7\times 6=42 $ (iii) Number of 1 digit no. $ =7 $ Total number of nos. $ =210+42+7=259 $