Arrays

Arrays are a way of showing a number using rows and columns. You can find arrays everywhere you look.

For example: –

How many trays do you see? How would you work that out?

Screen Shot 2014-02-24 at 7.24.56 AM  How many eggs are there in this box?

Screen Shot 2014-02-24 at 7.25.13 AMHow many gummy bears om this plate?

Screen Shot 2014-02-24 at 7.24.42 AM

How many orange dots can you see?

Screen Shot 2014-02-24 at 7.23.50 AM

twistlin

You are going to be asked to find arrays for certain numbers. You will be using blocks or drawing pictures to do so in your math journal.

Screen Shot 2014-02-24 at 7.25.41 AMThe number 2 and 4 are called FACTORS. The answer (8) is called a PRODUCT.

The equation you can write is :-  2 x 4 = 8 ……………  or …………… 4 x 2 = 8

twistlin

In your math journal you should record your investigation like this.

Screen Shot 2014-02-24 at 7.46.14 AM

Every number can be multiplied by itself and one to give the right answer. Because every number has an array like the first one (1 x ?) we don’t need to do that one for any number. HOWEVER …. there are some numbers that only have that array! These are called PRIME NUMBERS – numbers that can only be made into an array of a long line, and that has factors of 1 and itself.

twistlin

Using blocks, find all the arrays possible that would make the following numbers. Write an equation and draw the arrays into your math journal.

REMEMBER…YOU DO NOT NEED TO DO AN ARRAY FOR THE NUMBER TIMES 1!

12, 18, 20, 24, 28, 30, 32, 36, 40, 42, 44, 45, 48

Extension

Find all the prime numbers between 1 – 50 using arrays to prove your answer.

 

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