9999乘8888除1111的簡便運算?

9999乘8888除1111的簡便運算?


=9999×(8888÷1111)
=(10000-1)×8
=10000×8-1×8
=80000-8
=79992



8888×1111+4444×7778=?簡便計算


8888×1111+4444×7778
=4444×2×1111+4444×7778
=4444×2222+4444×7778
=4444×(2222+7778)
=4444×10000
=44440000



0.1111……+0.2222……+0.33333………………+0.878787……+0.8888……+0.898989……


0.1111……+0.2222……+0.33333………………+0.878787……+0.8888……+0.898989……
=(1+2+..+9)*(1/9)+(10+11+…+89)(1/99)
=45/9+3960/99=4455/99=495/11=45