What is the rule for this chart?

Question

1 | 1
2 | 3
3 | 6
4 |10
5 | 15

Answer 1

you are adding the first digit on the right to the second digit on the left, then you are getting the second on the right. to this one you are adding the third on the left- getting the third on the right etc.

Answer 2

The numbers on the left are simply progressive integers.
Add the number on the right to the next one up on the left and use it as the next one up on the right.

1 + 2 = 3
3 + 3 = 6
6 + 4 = 10
10 + 5 = 15

Answer 3

Notice that for the number n on the left, the number on the right is 1 + 2 + 3 + ... + n. A simpler way to write this sum is
n(n+1)/2.

Answer 4

The pattern is established by adding a particular position in the right column, with the subsequent number in the left column .
For example, 6 (rt. column) + 4 (lft. column) = 10
10(rt. column) + 5(lft. column) = 15.