654+823-554怎么简算
问题描述：
654+823-554怎么简算
还有9+99+999+9999
23×100.2
迅速回答
答
654+823-554
=(554+100)+823-554
=554-554+100+823
=923
9+99+999+9999
=(10-1)+(100-1)+(1000-1)+(10000-1)
=10+100+1000+10000-1-1-1-1
=11110-4
=11106
23×100.2
=23×（100+0.2）
=23×100+23×0.2
=2300+4.6
=2304.6