Giải thích các bước giải:
\(\begin{array}{l}
a)\,4 \times 9 \times 25 = 4 \times 25 \times 9 = 100 \times 9 = 900\\
b)\,72 \times 1000:100 = 72 \times 10 = 720\\
c)\,2008 \times 99 + 2008 = 2008 \times \left( {99 + 1} \right) = 2008 \times 10 = 20080\\
d)\,99 - \underbrace {9 + 9 + 9 + 9 + ... + 9}_{11\,chu\,so\,9} = 90 + \underbrace {9 + 9 + ... + 9}_{10\,chu\,so\,9} = 90 + 9 \times 10 = 90 + 90 = 180\\
e)\,624 \times 725 + 725 \times 376 = \left( {624 + 376} \right) \times 725 = 1000 \times 725 = 725000\\
g)\,72 \times 72 + 72 \times 38 - 72 \times 10 = 72 \times \left( {72 + 38 - 10} \right) = 72 \times 100 = 7200\\
h)\,38 + 38 \times 2 + 3 \times 38 + 38 \times 5 = 38 \times \left( {1 + 2 + 3 + 5} \right) = 38 \times 11 = 418\\
i)\,65 \times 3 + 5 \times 65 + 3 \times 65 = 65 \times \left( {3 + 5 + 3} \right) = 65 \times 11 = 715\\
k)\,704 \times 153 - 153 \times 200 - 153 \times 4 = 153 \times \left( {704 - 200 - 4} \right) = 153 \times 500 = 76500\\
l)\,\left( {145 \times 99 + 145} \right) - \left( {143 \times 101 - 143} \right) = \left( {145 \times 100} \right) - \left( {143 \times 100} \right) = 14500 - 14300 = 200
\end{array}\)
