Question

Use Gauss's approach to find the sum for 1+2+3+4+...+999

Answer 1

Sn=(a₁+an)n/2

Data:
a₁=1
an=999
n=999

Sn=(1+999)*999 /2=(1000)*999/2=999000/2=499500

Answer: the sum is 499500

Answer 2

1+999=1000
$\frac{999}{2}$
=499.5

The sum
=1000*499.5
=499500