Number System Practice Test 4

Question : 10 of 40

Marks: +1, -0

1 + 2 + 3 …+ 27 + 26 + 25 + … + 3 + 2 + 1 is equal to:

Solution:

1 + 2 + 3 … + 27 =

{27(27+1)}/2=378

1 + 2 + 3 + … + 26 =

{26(26+1)}/2=351

So, 1 + 2 + 3 … + 27 + 26 + 25 + … + 3 + 2 + 1
= 378 + 351 = 729.

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