Find the sum of first 123 even natural number.

Answer

The sum of the first 123 even natural numbers is 15252.

Explanation

2, 4, 6, …., `2_(n)` are the even natural numbers.
Here, `a=t_(1)=2,t_(2)=4,t_(3)=6,...`
`d=t_(2)-t_(1)=4-2=2,n=123`
`S_(n)=(n)/(2)[2a+(n-1)s]` …(Formula)
`thereforeS_(123)=(123)/(2)[2xx2+(123-1)xx21]` M ...(Substituting the values)
`=(123)/(2)(4+122xx2)`
`=(123)/(2)(4+244)`
`=(123)/(2)xx248`
`123xx124`
`thereforeS_(123=15252.`