①1+2+3+….…+1999 ②2000-3-6-9-……-51①1+2+3+….…+1999 ②2000-3-6-9-……-51-54这两题的步骤
问题描述:
①1+2+3+….…+1999 ②2000-3-6-9-……-51
①1+2+3+….…+1999 ②2000-3-6-9-……-51-54这两题的步骤
答
①1+2+3+….…+1999 ②2000-3-6-9-……-51
①1+2+3+….…+1999 ②2000-3-6-9-……-51-54这两题的步骤