Arithmetic Grade Three
Lesson Sixty-six: Doubles
Take a look at this example:
This example shows that 9 x 6 equals 9 x 3 + 9 x 3. Notice that 3 is half of
6. Also notice that 27 is exactly half of 54. Keep in mind that 3 x 9 = 27
and that 6 x 9 is 54. So, 3 x 9 is half of 6 x 9.
Here's another example:
One is half of two. So, 2 x 10 = 1 x 10 + 1 x 10.
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