Q. How many 10 digits numbers can be written by using digits 9 and 2?
A) $\ ^{10}C_{1} \times {\ ^{9}C}_{2}$
B) $2^{10}$
C) ${\ ^{10}C}_{2}$
D) $10!$
Explanation
(b)
Total number of numbers$= 2 \times 2 \times 2\ldots 10$ times$= 2^{10}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.