If ${{U}_{n}}=n({{n}^{2}}+1)$ evaluate U₅ – U₄

Simplify $\frac{1\tfrac{7}{8}\times 2\tfrac{2}{5}}{6\tfrac{3}{4}\div \tfrac{3}{4}}$

In what number base is the addition of 465 + 24 + 225 =1050

If ${{9}^{(2-x)}}=3$, find x

Multiply $2.7\times {{10}^{-4}}$ by $6.3\times {{10}^{6}}$ and leave your answer in standard form