In the statement $3\times5=15$3×5=15 we have a product (which is the answer of $15$15), and a factor pair of $3$3 and $5$5. The numbers that multiply together to give us the product are factors, when we have 2 of them that multiply to give us a product they are a factor pair. There is another factor pair for 15. Can you find it?
Sometimes there is more than one factor pair. For example, the number 12. Could be written as
$2\times6=12$2×6=12
$3\times4=12$3×4=12
$1\times12=12$1×12=12
So $12$12 has $3$3 factor pairs. 2 and 6, 1 and 12, 3 and 4.
Every number will have at least one factor pair. Prime numbers have only one factor pair, of $1$1 and itself. For example $7$7. It's only factor pair is $1$1 and $7$7.
Let's find the factor pairs for the number $6$6.
$\times$× | $1$1 | $2$2 | $3$3 | $4$4 | $5$5 | $6$6 |
---|---|---|---|---|---|---|
$1$1 | $1$1 | $2$2 | $3$3 | $4$4 | $5$5 | $6$6 |
$2$2 | $2$2 | $4$4 | $6$6 | $8$8 | $10$10 | $12$12 |
$3$3 | $3$3 | $6$6 | $9$9 | $12$12 | $15$15 | $18$18 |
$4$4 | $4$4 | $8$8 | $12$12 | $16$16 | $20$20 | $24$24 |
$5$5 | $5$5 | $10$10 | $15$15 | $20$20 | $25$25 | $30$30 |
$6$6 | $6$6 | $12$12 | $18$18 | $24$24 | $30$30 | $36$36 |
Using the table we can find all the numbers that multiply to give $6$6. We will only count factor pairs once, so, $1\times6$1×6is the same as $6\times1$6×1. So $1$1 and $6$6 are one set of factors for the number $6$6.
Using the table, what are the other factor pairs of $6$6?
Using the table we can look for all the numbers that multiply together to give $6$6.
The factor pairs of 6 are:
$59$59 is a prime number.
Which of the following options is a factor pair of $59$59?
$56$56 and $3$3
$1$1 and $59$59
If we multiply $4$4 by $14$14, we get $56$56, so $4$4 and $14$14 make a factor pair of $56$56.
Which of the following options is also a factor pair of $56$56?
$14$14 and $2$2
$4$4 and $7$7
$8$8 and $7$7
$2$2 and $2$2
Complete the table below, listing all factor pairs of the number $15$15.
Factor pairs of $15$15 |
---|
$\left(1,\editable{}\right)$(1,) |
$\left(\editable{},5\right)$(,5) |
Is $15$15 prime or composite?
$15$15 is a composite number.
$15$15 is a prime number.