3.14×101²-99²×3.14
=3.14×(101²-99²)
=3.14×(101+99)×(101-99)
=3.14×200×2
=628×2
=1256
3.14乘101乘101减99乘99乘以3.14
=3.14x101x101-99x99x3.14
=3.14(100+1)(100+1)-3.14(100-1)(100-1)
=3.14(10000+100+100+1)-3.14(10000-100-100+1)
=3.14(10000+200+1-10000+200-1)
=3.14x200
=628