Let the first natural number be A 1 And the last one be an, then according to the formula: (A 1+an) × n/2 = 49, that is, (A 1+an) × n = 98, where A 1, an,. Because it is a continuous natural number, An=A 1+n- 1, that is, (2× a 1+n- 1 )× n = 98.

Decomposition factor: 98 = 2× 7× 7.

1、98= 14×7

If n=7, A 1 = 4, an =104+5+6+7+8+9+10 = 49.

If n= 14, there is no solution.

2、98=2×49

If n=2, a 1 = 24, an = 25 24+25 = 49.

If n=49, there is no solution.

3. When "several" can be expressed as "1", the answer is 49.