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5√32 ?

$$5\sqrt{32} \\ =5\sqrt{16\cdot 2} \\ =5 \underbrace{\sqrt{16}}_{=4} \cdot \sqrt{2} \\ =5\cdot 4 \cdot \sqrt{2} \\ =20 \cdot \sqrt{2} \quad | \quad \boxed{\ \sqrt{2}= 1.41421356237 \ }\\ = 20 \cdot 1.41421356237\\ =28.2842712475$$