1. Number

Middle Years

Select all the prime numbers from each of these lists:

a

$3$3

A

$10$10

B

$12$12

C

$4$4

D

$5$5

E

$6$6

F

b

$14$14

A

$7$7

B

$15$15

C

$16$16

D

$13$13

E

$11$11

F

c

$21$21

A

$19$19

B

$27$27

C

$17$17

D

$22$22

E

$1$1

F

Easy

Approx a minute

A number has the following factor tree:

A number has the following factor tree:

This question is about prime factorisations, and the difference between index form and expanded form.

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