Find the sum of all numbers of 1 ~ 2009 continuous natural numbers It's the sum of the numbers. For example, the sum of 11 and 12 is 5

Find the sum of all numbers of 1 ~ 2009 continuous natural numbers It's the sum of the numbers. For example, the sum of 11 and 12 is 5

The analysis may as well seek the sum of all numbers from 0 to 1999, and then seek the sum of all numbers from 2000 to 2009
Solution (1 + 9 × 3) × (2000 △ 2)
=28×1000
=28000
2×10+1+2+… +9
=20+45
=65
28000+65
=28065
Answer: the sum of the figures is 28065
That's it!