Question

How many four digits numbers are in all and​

Answer 1

$\Large{\underline{\underline{\bf{Answer:-}}}}$

❥ The smallest 4 digit number = 1000

❥ The largest 4 digit number = 9999

$\Large{\underline{\underline{\bf{SoLuTion:-}}}}$

1000, 1001, 1002, ........ 9999 are in A.P

(Arithmetic Progression)

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❥ Consider the formula,

aₙ = a + ( n - 1 )d

Where

❥ aₙ = The last term

❥ a = The first term

❥ n = Number of terms

❥ d = Common difference

$9999 = 1000 + (n - 1) 1 \\9999 = 1000 + n - 1 \\9999 - 1000 + 1 = n \\n = 9000$

Therefore, there are 9000 numbers from 1000 to 9999

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Answer 2

Answer:

there are 9000 numbers from 1000 to 9999