Question

X= { The units digit of the sum of 10 consective natural numbers } Find X. X = {10 लगातार प्राकृतिक संख्याओं के योग की इकाइयाँ} X खोजें।


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Answer 1

It will always be 5.

Explanation

Let the 10 consecutive natural numbers be

n, n+1, n+2, n+3, ....n+9

the sum would be

n + (n+1) + (n+2) + ....... + (n+9)

= (n + n + n ..... 10 terms) + (1 + 2 + 3 +...+9)

= 10n + 45

the term 10n will have 0 as unit place and when added with 45 will have 5 as unit digit.