Q:

insert comma between numbers

I have the following numbers rows and I want to insert a comma between the numbers?
6   7   9   51  64  68  79  102 116 128 148 155 184 202 273 283 292 1
7   8   10  52  65  69  80  103 117 129 149 156 185 203 274 284 293 2
8   9   11  53  66  70  81  104 118 130 150 157 186 204 275 285 294 3
9   10  12  54  67  71  82  105 119 131 151 158 187 205 276 286 295 4
10  11  13  55  68  72  83  106 120 132 152 159 188 206 277 287 296 5
11  12  14  56  69  73  84  107 121 133 153 160 189 207 278 288 297 6
12  13  15  57  70  74  85  108 122 134 154 161 190 208 279 289 298 7
13  14  16  58  71  75  86  109 123 135 155 162 191 209 280 290 299 8
14  15  17  59  72  76  87  110 124 136 156 163 192 210 281 291 300 9

A:

ImportString[
 StringReplace[
  "{6 7 9 51 64 68 79 102 116 128 148 155 184 202 273 283 292 1 7 8 \
10 52 65 69 80 103 117 129 149 156 185 203 274 284 293 2 8 9 11 53 66 \
70 81 104 118 130 150 157 186 204 275 285 294 3 9 10 12 54 67 71 82 \
105 119 131 151 158 187 205 276 286 295 4 10 11 13 55 68 72 83 106 \
120 132 152 159 188 206 277 287 296 5 11 12 14 56 69 73 84 107 121 \
133 153 160 189 207 278 288 297 6 12 13 15 57 70 74 85 108 122 134 \
154 161 190 208 279 289 298 7 13 14 16 58 71 75 86 109 123 135 155 \
162 191 209 280 290 299 8 14 15 17 59 72 76 87 110 124 136 156 163 \
192 210 281 291 300 9}", "{" | "}" -> ""], "List", 
 "LineSeparators" -> " "]

{6,7,9,51,64,68,79,102,116,128,148,155,184,202,273,283,292,1,7,8,10,52,65,69,80,103,117,129,149,156,185,203,274,284,293,2,8,9,11,53,66,70,81,104,118,130,150,157,186,204,275,285,294,3,9,10,12,54,67,71,82,105,119,131,151,158,187,205,276,286,295,4,10,11,13,55,68,72,83,106,120,132,152,159,188,206,277,287,296,5,11,12,14,56,69,73,84,107,121,133,153,160,189,207,278,288,297,6,12,13,15,57,70,74,85,108,122,134,154,161,190,208,279,289,298,7,13,14,16,58,71,75,86,109,123,135,155,162,191,209,280,290,299,8,14,15,17,59,72,76,87,110,124,136,156,163,192,210,281,291,300,9}

Or even simpler:
ImportString["6 7 9 51 64 68 79 102 116 128 148 155 184 202 273 283 292 1 7 8 10 52 65 \
69 80 103 117 129 149 156 185 203 274 284 293 2 8 9 11 53 66 70 81 104 118 130 150 157 \
186 204 275 285 294 3 9 10 12 54 67 71 82 105 119 131 151 158 187 205 276 286 295 4 10 \
11 13 55 68 72 83 106 120 132 152 159 188 206 277 287 296 5 11 12 14 56 69 73 84 107 121 \
133 153 160 189 207 278 288 297 6 12 13 15 57 70 74 85 108 122 134 154 161 190 208 279 \
289 298 7 13 14 16 58 71 75 86 109 123 135 155 162 191 209 280 290 299 8 14 15 17 59 72 \
76 87 110 124 136 156 163 192 210 281 291 300 9", "Table"] 

