5. Multiplication fluency
5.04 Multiply by 8
Lesson
Are you ready?
Multiplication looks at equally sized groups. Doubling means multiplying equally sized groups by $2$2. Let's try this problem to remember how.
$9\times2$9×2
Learn
$4$4 groups is twice (two times) as many as $2$2 groups. $8$8 groups is twice (two times) as many as $4$4 groups. Let's look at how to multiply numbers by $8$8 using a Double, Double, Double strategy.
Apply
$8\times5$8×5
Remember!
You can use the Double, Double, Double strategy to multiply a number by $8$8. To do this, double the number, double the answer, then double the answer again.