Prime numbers from 1 to 100
- 1
- 2 (prime)
- 3 (prime)
- 4
- 5 (prime)
- 6
- 7 (prime)
- 8
- 9
- 10
- 11 (prime)
- 12
- 13 (prime)
- 14
- 15
- 16
- 17 (prime)
- 18
- 19 (prime)
- 20
- 21
- 22
- 23 (prime)
- 24
- 25
- 26
- 27
- 28
- 29 (prime)
- 30
- 31 (prime)
- 32
- 33
- 34
- 35
- 36
- 37 (prime)
- 38
- 39
- 40
- 41 (prime)
- 42
- 43 (prime)
- 44
- 45
- 46
- 47 (prime)
- 48
- 49
- 50
- 51
- 52
- 53 (prime)
- 54
- 55
- 56
- 57
- 58
- 59 (prime)
- 60
- 61 (prime)
- 62
- 63
- 64
- 65
- 66
- 67 (prime)
- 68
- 69
- 70
- 71 (prime)
- 72
- 73 (prime)
- 74
- 75
- 76
- 77
- 78
- 79 (prime)
- 80
- 81
- 82
- 83 (prime)
- 84
- 85
- 86
- 87
- 88
- 89 (prime)
- 90
- 91
- 92
- 93
- 94
- 95
- 96
- 97 (prime)
- 98
- 99
- 100
- 101 (prime)
- 102
- 103 (prime)
- 104
- 105
- 106
- 107 (prime)
- 108
- 109 (prime)
- 110
- 111
- 112
- 113 (prime)
- 114
- 115
- 116
- 117
- 118
- 119
- 120
- 121
- 122
- 123
- 124
- 125
- 126
- 127 (prime)
- 128
- 129
- 130
- 131 (prime)
- 132
- 133
- 134
- 135
- 136
- 137 (prime)
- 138
- 139 (prime)
- 140
- 141
- 142
- 143
- 144
- 145
- 146
- 147
- 148
- 149 (prime)
- 150
- 151 (prime)
- 152
- 153
- 154
- 155
- 156
- 157 (prime)
- 158
- 159
- 160
- 161
- 162
- 163 (prime)
- 164
- 165
- 166
- 167 (prime)
- 168
- 169
- 170
- 171
- 172
- 173 (prime)
- 174
- 175
- 176
- 177
- 178
- 179 (prime)
- 180
- 181 (prime)
- 182
- 183
- 184
- 185
- 186
- 187
- 188
- 189
- 190
- 191 (prime)
- 192
- 193 (prime)
- 194
- 195
- 196
- 197 (prime)
- 198
- 199 (prime)
- 200
Prime numbers from 1 to 100stringmash.com/prime-number-chart
Reading the chart
The marked numbers are prime. A prime has exactly two factors, 1 and itself. Every other number above 1 is composite, a product of smaller primes.
There are 25 primes up to 100 and 46 up to 200. 1 is neither prime nor composite. It has only one factor.
To test a number that isn't on the chart, type it into the box above. You get its prime factors, and a prime comes back as just itself.
List of primes up to 200
The primes up to 100 are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97.
Between 101 and 200 they are 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199.
The Sieve of Eratosthenes
Tick the blank box above the chart and print it. Cross out 1. Circle 2, then cross out every multiple of 2. Move on to the next number that isn't crossed out, circle it and cross out its multiples. Repeat.
For a 1 to 100 grid you can stop after 7. The next prime is 11, and 11 × 11 = 121 is already off the chart, so any composite left would have a factor you have already used. Everything still standing is prime.
Patterns worth spotting
Apart from 2, every prime is odd. Apart from 2 and 5, every prime ends in 1, 3, 7 or 9.
On a ten-wide grid the primes line up in four columns: 1, 3, 7 and 9. Twin primes, pairs two apart such as 11 and 13 or 71 and 73, sit next to each other in those columns.
Questions
Is 1 a prime number?
No. A prime needs exactly two different factors, and 1 has only one. Leaving it out also keeps every number's prime factorisation unique.
Is 2 the only even prime?
Yes. Every other even number has 2 as a factor, so it has at least three factors.
Why is 91 not prime?
91 is 7 × 13. It looks prime because it is odd and doesn't end in 5, which makes it a favourite trick question.
Sources
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