1.

Find the sum of the nature number between 100 and 100 which divisible by 11​

Answer»

CORRECT QUESTION :

find the sum of the natural numbers between 1 to 100 which divisible by 11

Solution :

Natural numbers between 1 to 100 which is divisible by 11 are :

  • 11 , 22 , 33 ,44 ........... 99

We need to find the sum of the NATURE number between 1 and 100 which divisible by 11.

an = a + (n - 1)d

  • a = 11
  • d = 11

99 = 11 + (n - 1)11

88 = (n - 1)11

88/11 = (n - 1)

8 + 1 = n

n = 9

\rm \: s_n = \frac{n}{2} \{2a + (n - 1)d \} \\ \\ \rm \: s_{9} = \frac{9}{2} \{22 + 8 \times 11 \} \\ \\ \rm \: s_9 = \frac{9}{2} \{22 + 88 \} \\ \\ \rm \: s_9 = \frac{9}{2} \times 110 \\ \\ \rm \: s_9 = 9 \times 55 \\ \\ \rm \: s_9 = 495

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