\[\boxed{\mathbf{3.}}\]
\[1)\ 543 \cdot 2849 \approx 500 \cdot 3000 =\]
\[= 1\ 500\ 000\]
\[2)\ 7560 \cdot 8092 \approx 8000 \cdot 8000 =\]
\[= 64\ 000\ 000\]
\[\mathbf{13.3.\ Квадрат\ и\ куб\ числа}\]
\[\boxed{\mathbf{1.}}\]
\[1)\ 5 \cdot 5 = 5^{2}\]
\[2)\ 4 \cdot 4 \cdot 4 = 4^{3}\]
\[3)\ 13 \cdot 13 \cdot 13 = 13^{3}\]
\[4)\ 100 \cdot 100 = 100^{2}\]
\[\boxed{\mathbf{2.}}\]
\[1)\ 2 \cdot 2 \cdot 2 \cdot 2 \cdot 2 \cdot 2 = 2^{6}\]
\[2)\ 3 \cdot 3 \cdot 3 \cdot 3 = 3^{4}\]
\[3)\ a \cdot a \cdot a \cdot a \cdot a \cdot a = a^{6}\]
\[\boxed{\mathbf{3.}}\]
\[1)\ 5^{2} + 6^{2} = 25 + 36 = 61\]
\[2)\ 3^{2} + 4^{2} = 9 + 16 = 25\]
\[3)\ 2^{3} + 3^{3} = 8 + 27 = 35\]
\[4)\ 4^{3} + 8^{2} = 64 + 64 = 128\]
\[5)\ 7^{2} - 3^{3} = 49 - 27 = 22\]