Rewrite \(640\) as its prime factors.
\[\sqrt{2\times 2\times 2\times 2\times 2\times 2\times 2\times 5}\]
Group the same prime factors into pairs.
\[\sqrt{(2\times 2)\times (2\times 2)\times (2\times 2)\times 2\times 5}\]
Rewrite each pair in exponent form.
\[\sqrt{{2}^{2}\times {2}^{2}\times {2}^{2}\times 2\times 5}\]
Use this rule: \(\sqrt{{x}^{2}}=x\).
\[(2\times 2\times 2)\sqrt{2\times 5}\]
Simplify.
\[8\sqrt{10}\]
Decimal Form: 25.298221
8*sqrt(10)
