1.各个数位上数的和等于12的三位数有多少个?2.一本书共124页,印刷排版这本书的页码,一共用多少数字?

58个921,912,129,219,192,291；813,831,138,318,183,381；822,282,228；840,804；714,741,147,174,417,471；723,732,237,273,327,372；750,705；606,660615,651,156,165,516,561；624,642,246,264,462,426,633,336,3...