问题
解答题
简便计算．
①7.7×7+7.7×2+7.7
②87.3×45+10.7×45+2×45
③（2.5+2.5+2.5+2.5）×2.5×8．
答案
①7.7×7+7.7×2+7.7，
=7.7×（7+2+1），
=7.7×10，
=77；
②87.3×45+10.7×45+2×45，
=（87.3+10.7+2）×45，
=100×45，
=4500；
③（2.5+2.5+2.5+2.5）×2.5×8，
=（2.5×4）×2.5×4×2，
=10×10×2，
=200．
