NIELIT Scientist B 2020 November: 118

Question

The number of $4$ digit numbers which contain not more than two different digits is:

• A. $576$
• B. $567$
• C. $513$
• D. $504$

Comments

9*10*10*10 – 9*9*8*7-9*9*8*6 = 576

total – (4,3) diff digit

---

Please explain too

---

https://testbook.com/question-answer/the-number-of-4-digit-numbers-which-contain-not-mo--600059f1119a81ae7204d232