4.99+4.99+4.99+0.04+4.99 怎么巧算

4.99+4.99+4.99+0.04+4.99 怎么巧算
4.99+4.99+4.99+0.04+4.99 怎么巧算

4.99+4.99+4.99+0.04+4.99 怎么巧算
=(4.99+0.01)+(4.99+0.01)+(4.99+0.01)+(4.99+0.01)=5+5+5+5=20

原式=5+5+5+5-0.01*4+0.04
=20-0.04+0.04
=20

(5-0.01)x4+0.04
=5x4-0.04+0.04
=20