1991+199.1+19.91+1.991.
1991+199.1+19.91+1.991.
求 算术 1991+199.1+19.91+1.991=?
19991+199.1+19.91+1.991 88.88*0.9+22.22*6.4 简算
1991×199219921992-1992×199119911991.
有一个边数为1991的凸多边形,在其1991个内角中最多有______个锐角.
1.991+1.992+1.993+...+2.001+2.002+2.003
巧算.19+199+1999+19999+1991+2+3+4+…+97+98+99+100.
1993×1993+1992×1992-1993×1992-1992×1991=______.
求方程(x+y)(x-y)=1991的整数解.
1-2+3-4+5-6+…+1991-1992+1993=______.
1.1+1.91+1.991+.+1.99(100个九)1
1.991约等于多少?要保留两位小数