There are many numbers from 1 to 1000 whose sum of its digits is 4. For example, 310, has a sum of 4 for its digits (3 + 1 + 0= 4).
If there are "b" numbers with this property and "a" of these are prime numbers, then determine the value of:
a
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b
2007-12-03 13:42:25 · 2 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
Here are the prime numbers:
2 3 5 7 11 13 17 19 23 29
31 37 41 43 47 53 59 61 67 71
73 79 83 89 97 101 103 107 109 113
127 131 137 139 149 151 157 163 167 173
179 181 191 193 197 199 211 223 227 229
233 239 241 251 257 263 269 271 277 281
283 293 307 311 313
Here are the numbers that meet the requirment:
1. 4
2. 13
3. 22
4. 31
5. 40
6. 103
7. 112
8. 121
9. 130
10. 202
11. 211
12. 220
13. 301
14. 310
15. 400
15 total
4 are prime numbers
4/15 or .26667
2007-12-03 14:01:38 · answer #1 · answered by Davyd R 3 · 0⤊ 0⤋
4, 13, 22, 31,40, 103,112,121, 130,211, 202, 301,310,400
b = 14
a = 4
a/b = 2/7
2007-12-03 21:53:58 · answer #2 · answered by ironduke8159 7 · 0⤊ 0⤋