4000-1-2-3-4-5-…-76-77-78=______.
4000-1-2-3-4-5-…-76-77-78=______.
科学探究的基本方法:1、______,2、______,3、______,4、______.
-1-2-3-4-…-100=______.
21.035里面有2个______,1个______,3个______和5个______,它的计算单位是______.
找规律填数:1,3,2,6,4,______,______,12,16,….
27046=2×______+7×______+4×______+6×______.
125×(4+8)=______×______+______×______.
1-2+3-4+5-6+…+2005-2006=______.
(1-2)(3-4)(5-6)…(99-100)=______.
1-2+3-4+5-6+…+1991-1992+1993=______.
计算:1-2+3-4+5-6+…+87-88=______.
1+2-3+4-5+…-99+100=______.