3×9=27,93×99=9207,993×999=992007,9993×9999=99920007,99…93(10
9999+999+99+9=? 简便计算
9×9+99×99+999×999+9999×9999+9999+999+99+9=?等于多少?
99-97+95-93……+5-3+2-1=? 简便算法
9999999999+999999999+99999999+99999+9999+999+99+9=?
9999×999×99×9+1+11+111+1111=(
1×9= 91×99= 991×999=找规律
100一99十98一97十96一95十94一93……十4一3十2一1=?
9χ99χ999χ9999χ99999χ999999χ999999χ999999χ9999999=
99的2次方=9801;999的2次方=998001;9999的2次方=9998001;99999的2次方=999980
77%×99+23%×99 = =
99+99×99+999×999×999等于=?用简便方法计算,
100+99……+2+1=?