9+99+99+999+9999+99999+999999+999999+9999999+99999999+999999999=?

(-9)+(-99)+(-999)+(-9999) 9999+999+99+9 9999+999+99+9 9999+999+99+9+6 巧算 简算9+99+999+9999 9+99+999+9999+...99999999 9+99+999+9999巧算 9999+999+99+9+8 9+99+999+9999+9999+99999=? 简算：9999+999+99+9=?） 简算9999+999+99+9+4 9+99+999+9999简便算法? 9999+999+99+9 简便计算 9＋99＋999＋9999 9+99+999+9999+99999+999999=? 9+99+999+9999简便计算 99+9+999+9999+4简便计算 9十99+999+9999+99999 9+99+999+9999+99999 = =