A simple algorithm for (1 / 18) / (2 / 3 + 1 / 6-1 / 2)

A simple algorithm for (1 / 18) / (2 / 3 + 1 / 6-1 / 2)

1/(18*2/3+18*1/6+18*1/2)=1/(12+3-9)=1/6

Choose a reasonable method to calculate. 3-6 / 15 + 5 / 6 + 25-12 + 5-18 + 7 / 3 + 1-12 + 5 / 6

3 / 15-1 / 6 + 5 / 6
=1/5+4/6
=1/5+2/3
=13/15
5 of 25-12-7 of 18
=25-(15/36+14/36)
=25-29/36
=24 and 7 / 36
2 / 3 + 1 / 6-5 / 12
=8/12+2/12-5/12
=5/12

1 * 2 + 3 * 4 + 5 * 6 + 7 * 8 +... + 49 * 50 thank you

The answer is 21450

1+（-2）+3+（-4）+5+（-6）+7+（-8）+…… 49+（-50）=（ ）

1+（-2）+3+（-4）+5+（-6）+7+（-8）+…… 49+（-50)
=-1+(-1)+(-1)+.+(-1）
=-1×25
=-25