（1）63²=（60+3）²
=60²+2×60×3+3²
=3600+360+9
=3939；
（2）98²
=（100-2）²
=100²-2×100×2+2²
=10000-400+4
=9604；
（3）700.1²
=（700+0.1）²
=700²+2×700×0.1+0.1²
=490000+140+0.01
=490140.01；
（4）499.9²
=（500-0.1）²
=500²-2×500×0.1+0.1²
=250000-100+0.01
=249900.01．