二点九乘以零点四五加上零点二九乘以四点二加上零点零二九乘以一拾三的简便方法?

问题描述:

二点九乘以零点四五加上零点二九乘以四点二加上零点零二九乘以一拾三的简便方法?

二点九乘以零点四五加上零点二九乘以四点二加上零点零二九乘以一拾三
=2.9×0.45+0.29×4.2+0.029×13
=2.9×(0.45+0.42+0.13)
=2.9