Question

How many numbers are exactly of four digits?

Answer 1

Answer:

here it is

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Answer 2

Answer:

9000

Step-by-step explanation:

four digit number start from 1000 and end at 9999

All number are in AP

a=1000

d=1

last term =9999 =tn

tn=a+(n-1)d

9999=1000+(n-1)1

9999-1000=n-1

8999+1=n

n=9000