13の性質
かけ算13の段 13×23は意味深な値になるよ
- 13 × 1 = 13
- 13 × 2 = 26
- 13 × 3 = 39
- 13 × 4 = 52
- 13 × 5 = 65
- 13 × 6 = 78
- 13 × 7 = 91
- 13 × 8 = 104
- 13 × 9 = 117
- 13 × 10 = 130
- 13 × 11 = 143
- 13 × 12 = 156
- 13 × 13 = 169
- 13 × 14 = 182
- 13 × 15 = 195
- 13 × 16 = 208
- 13 × 17 = 221
- 13 × 18 = 234
- 13 × 19 = 247
- 13 × 20 = 260
- 13 × 21 = 273
- 13 × 22 = 286
- 13 × 23 = 299
- 13 × 24 = 312
- 13 × 25 = 325
- 13 × 26 = 338
- 13 × 27 = 351
- 13 × 28 = 364
- 13 × 29 = 377
- 13 × 30 = 390
- 13 × 31 = 403
- 13 × 32 = 416
- 13 × 33 = 429
- 13 × 34 = 442
- 13 × 35 = 455
- 13 × 36 = 468
- 13 × 37 = 481
- 13 × 38 = 494
- 13 × 39 = 507
- 13 × 40 = 520
- 13 × 41 = 533
- 13 × 42 = 546
- 13 × 43 = 559
- 13 × 44 = 572
- 13 × 45 = 585
- 13 × 46 = 598
- 13 × 47 = 611
- 13 × 48 = 624
- 13 × 49 = 637
- 13 × 50 = 650
- 13 × 51 = 663
- 13 × 52 = 676
- 13 × 53 = 689
- 13 × 54 = 702
- 13 × 55 = 715
- 13 × 56 = 728
- 13 × 57 = 741
- 13 × 58 = 754
- 13 × 59 = 767
- 13 × 60 = 780
- 13 × 61 = 793
- 13 × 62 = 806
- 13 × 63 = 819
- 13 × 64 = 832
- 13 × 65 = 845
- 13 × 66 = 858
- 13 × 67 = 871
- 13 × 68 = 884
- 13 × 69 = 897
- 13 × 70 = 910
- 13 × 71 = 923
- 13 × 72 = 936
- 13 × 73 = 949
- 13 × 74 = 962
- 13 × 75 = 975
- 13 × 76 = 988
- 13 × 77 = 1001
- 13 × 78 = 1014
- 13 × 79 = 1027
- 13 × 80 = 1040
- 13 × 81 = 1053
- 13 × 82 = 1066
- 13 × 83 = 1079
- 13 × 84 = 1092
- 13 × 85 = 1105
- 13 × 86 = 1118
- 13 × 87 = 1131
- 13 × 88 = 1144
- 13 × 89 = 1157
- 13 × 90 = 1170
- 13 × 91 = 1183
- 13 × 92 = 1196
- 13 × 93 = 1209
- 13 × 94 = 1222
- 13 × 95 = 1235
- 13 × 96 = 1248
- 13 × 97 = 1261
- 13 × 98 = 1274
- 13 × 99 = 1287
- 13 × 100 = 1300
13 の段は正直あまり使わない。13 で割る割り算をちょっとでも速くしたい人は覚えるといいかもしれない。ここでは 299 をピックアップしてみます。
13 × 23 = 299
これはどことなく
12 × 25 = 300
を思いださせます。私はこの 2 つの式をセットで覚えていました。13 の倍数を覚えていると「299 は素数でない」という知識がつきます。覚えていれば中学受験や大学受験でいきるかも？
