# How do you multiply 2(6+10)?

May 8, 2016

32

#### Explanation:

$\textcolor{b l u e}{\text{Shortcut method}}$

$2 \times 16 = 32$

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$\textcolor{b l u e}{\text{Teaching bit:}}$

suppose you had $2 \left(a + b\right)$

This is 2 lots of $\left(a + b\right)$

So $2 \left(a + b\right) \text{ "->" } \left(a + b\right) + \left(a + b\right)$

Which is: $a + a + b + b = 2 a + 2 b$

From this you can observe that you get the same answer if you just multiply everything inside the brackets by 2.

Suppose you had $= - 3 \left(a + b\right) = - 3 a - 3 b$

Suppose you had $- 3 \left(a - 4 b\right) = - 3 a + 12 b$

Suppose you had $5 \left(\frac{1}{5 a} + \frac{b}{10}\right) = \frac{5}{5 a} + \frac{5 b}{10} = \frac{1}{a} + \frac{b}{2}$