NUMBERS • PRIME NUMBERS 33
Prime numbers
up to 100
This table shows all the prime
numbers from 1 to 100.
Prime numbers
are shaded
dark purple
2 is the only even
prime. All other even
numbers can be divided
by 2 so are not prime
1 is not a prime number
because it doesn’t have two
different factors – 1 and itself
are the same number!
Non-primes
are shaded
pale purple
The largest prime
The ancient Greek
mathematician Euclid worked
out that we can never know
the largest possible prime
number. The largest prime we
currently know is more than
22 million digits long! It’s
written like this:
Prime or not prime?
There’s a simple trick we can use to check whether a number
is prime – just follow the steps on this chart:
CAN YOU DIVIDE THIS NUMBER
EXACTLY BY 2, 3, 5, OR 7?
PICK A WHOLE NUMBER
FROM 2 TO 100
IT’S A PRIME
NO YES
IT’S NOT A PRIME
2
74 207 281
−1
This means “multiply 2
by itself 74 207 281
times, then subtract 1”
1 2 3 4 5 6 7 8 9 10
11 12 13 14 15 16 17 18 19 20
21 22 23 24 25 26 27 28 29 30
31 32 33 34 35 36 37 38 39 40
41 42 43 44 45 46 47 48 49 50
61 62 63 64 65 66 67 68 69 70
91 92 93 94 95 96 97 98 99 100
81 82 83 84 85 86 87 88 89 90
71 72 73 74 75 76 77 78 79 80
51 52 53 54 55 56 57 58 59 60
REAL WORLD MATHS
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