5.6X69.32+138.64x0.05+69.32x4.3用简便算法?

5.6X69.32+138.64x0.05+69.32x4.3
=5.6×69.32+69.32×2×0.05+69.32×4.3
=69.32×（5.6+0.1+4.3）
=69.32×10
=693.2请问为什么0.05变成0.1了呢？请讲解一下，2×0.05=0.1