递等式计算,能巧算的要巧算.161x48-48x51+110x2 9.09+99.09+999.09+9999.09

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递等式计算,能巧算的要巧算.161x48-48x51+110x2 9.09+99.09+999.09+9999.09

161x48-48x51+110x2
=(161-51)x48+110x2
=110x48+110x2
=110x(48+2)
=110x50
=5500
9.09+99.09+999.09+9999.09
=9+99+999+9999+0.09x4
=(10-1)+(100-1)+(1000-1)+(10000-1)+0.09x4
=11110-4+0.36
=11106.36