Using the properties of decimals and the distributive rule, can you quickly find \( 15\% \) of 64?
Hint: \( 15 \% = 10\% + 5\% \).
Using the distributive rule, which of these are equivalent to \( 7 \times 64 + 7 \times 6? \)
Using the perfect square identity, which of these is equivalent to \( 81^2 ? \)
Hint: \( (a+b)^2 = (a+b) \times ( a +b) \).
Using the difference of two squares identity, which of these is equivalent to \( 5.7 \times 6.3 ? \)
Hint: \( a^2 - b^2 = (a+b)(a-b) \).
\[35 \times 28 = \, ? \]
(No calculators! Use your head and the hint above.)