9.9×10.1巧算

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9.9×10.1巧算9.9×10.1巧算9.9×10.1巧算9.9*10.1=9.9*(10+0.1)=99+0.99=99.999.9X10.1=9.9X10+9.9X0.1=99+0.99=99.

9.9×10.1巧算
9.9×10.1巧算

9.9×10.1巧算
9.9*10.1
=9.9*(10+0.1)
=99+0.99
=99.99

9.9X10.1
=9.9X10+9.9X0.1
=99+0.99
=99.99

=(10-0.1)(10+0.1)
=10^2 - 0.1^2
=100-0.01
=99.99

原式=(10-0.1)×(10+0.1)
=10方-0.1方
=100-0.01
=99.99