9999999999+999999999+99999999+99999+9999+999+99+9=?
9999999999+999999999+99999999+99999+9999+999+99+9=?
9+99+999+9999
9×9+99×99+999×999+9999×9999+9999+999+99+9=?等于多少?
9999×999×99×9+1+11+111+1111=(
111+222+333+444+555+666+777+888++++++++++++++++++++++999=?
(9999+9997+.+9001)-(1+3+.+999)
用乘法分配律简便法计算:9+99+99+999+4
巧算 (1)5×999+5+99×7+7+3×9+3 = = = = = (2)99999+
9又1/7+99又2/7+999又3/7+9999又4/7+99999又5/7+999999又6/7简算
1+2+3+4+5+6+7+8+9+10+11+12=?
1-3+5-7+9-11+…+97-99+100=?
1+3+5+7+9+⋯+97+99 用脱式简便计算.