Express the following as a Hindu-Arabic numeral:

$\mathrm{DCCLXIV}$

Express the following as a Hindu-Arabic numeral:

$\mathrm{CCXX}$

Express the following as a Hindu-Arabic numeral:

$\mathrm{MVI}$

Express the following as a Hindu-Arabic numeral:

$\text{ LXXXIV }$

Estimate and compare with the actual sum :

$760+683$

Estimate and compare with the actual sum:

$9,864+2,349$

Find the estimated quotient for $473÷19$.

Express the following numbers as Roman numerals :

$446$