\[\boxed{\text{884\ (884).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[\textbf{а)}\ \frac{\sqrt{\sqrt{18} - 3} \cdot \sqrt{\sqrt{18} + 3}}{\sqrt{6}} = \sqrt{1,5}\]
\[\frac{\sqrt{\sqrt{18} - 3} \cdot \sqrt{\sqrt{18} + 3}}{\sqrt{6}} = \sqrt{1,5}\]
\[\frac{\sqrt{\left( \left( \sqrt{18} \right)^{2} - 3^{2} \right)}}{\sqrt{6}} = \sqrt{1,5}\]
\[\frac{\sqrt{9}}{\sqrt{6}} = \sqrt{1,5}\]
\[\sqrt{\frac{3}{2}} = \sqrt{1,5}\]
\[\sqrt{1,5} = \sqrt{1,5}.\]
\[\textbf{б)}\ \frac{\sqrt{10}}{\sqrt{7 + \sqrt{24}} \cdot \sqrt{7 - \sqrt{24}}} = \sqrt{0,4}\]
\[\ \frac{\sqrt{10}}{\sqrt{7 + \sqrt{24}} \cdot \sqrt{7 - \sqrt{24}}} = \sqrt{0,4}\]
\[\frac{\sqrt{10}}{\sqrt{\left( 7^{2} - \left( \sqrt{24} \right)^{2} \right)}} = \sqrt{0,4}\]
\[\frac{\sqrt{10}}{\sqrt{49 - 24}} = \sqrt{0,4}\]
\[\sqrt{\frac{10}{25}} = \sqrt{0,4}\]
\[\sqrt{0,4} = \sqrt{0,4}.\]
\[\boxed{\text{884.}\text{\ }\text{ОК\ ГДЗ\ -\ домашка\ на\ 5}}\]
\[1000 \cdot 21 = 21\ 000 = {144,9}^{2}\]
\[1001 \cdot 21 = 21\ 021 = {144,9}^{2}\]
\[1002 \cdot 21 = 21\ 042 = {145,1}^{2}\]
\[Подобным\ \ образом\ \]
\[проверяем\ остальные\ числа,\]
\[пока\ не\ дойдем\ до\ числа\ 1029:\]
\[1029 \cdot 21 = 21\ 609 = 147^{2}.\]
\[Ответ:1029.\]