你好，具体解法如下：
6.9+6.9×99
=6.9×1+6.9×99
=6.9×(1+99)
=6.9×100
=690
6.9+6.9×99
=6.9x(1+99)
=6.9x100
=690
6.9+6.9×99
=6.9×（1+99）
=6.9×100
=690
6.9+6.9×99
=6.9+（1+99）
=6.9×100
=690
6.9+6.9×99，简便计算就是反向乘法分配律。具体步骤如下：
6.9+6.9×99
＝6.9×1+6.9×99
＝6.9×（1+99）
＝6.9×100
＝690
内容全部来源于网络收集，如有侵权，请联系网站删除！
QQ：24596024