Answer:
{n*(n+1) } /2
Step-by-step explanation:
The clearest pattern is that the last digit is multiplied by the number after it and then the multiplication is divided by 2.
1 is multiplied by 2, then divided by 2.
2 is multiplied by 3, then divided by 2.
3 is multiplied by 4, then divided by 2.
So, the pattern is:
{n*(n+1) }/2.
Hope this helped!
