A prime reciprocal magic square is a magic square using the decimal digits of the reciprocal of a prime number.
Consider a number divided into one, like 1/3 or 1/7. In base ten, the remainder, and so the digits, of 1/3 repeats at once: 0·3333... However, the remainders of 1/7 repeat over six, or 7-1, digits: 1/7 = 0·142857142857142857... If you examine the multiples of 1/7, you can see that each is a cyclic permutation of these six digits:
1/7 = 0·1 4 2 8 5 7... 2/7 = 0·2 8 5 7 1 4... 3/7 = 0·4 2 8 5 7 1... 4/7 = 0·5 7 1 4 2 8... 5/7 = 0·7 1 4 2 8 5... 6/7 = 0·8 5 7 1 4 2...If the digits are laid out as a square, it is obvious that each row will sum to 1+4+2+8+5+7, or 27, and only slightly less obvious that each column will also do so, and consequently we have a magic square:
1 4 2 8 5 7 2 8 5 7 1 4 4 2 8 5 7 1 5 7 1 4 2 8 7 1 4 2 8 5 8 5 7 1 4 2However, neither diagonal sums to 27, but all other prime reciprocals in base ten with maximum period of p-1 produce squares in which all rows and columns sum to the same total.
Other properties of Prime Reciprocals: Midy's theorem
The repeating pattern of an even number of digits in the quotients when broken in half are the nines-complement of each half:
1/7 = 0.142,857,142,857 ... +0.857,142 --------- 0.999,999 1/11 = 0.09090,90909 ... +0.90909,09090 ----- 0.99999,99999 1/13 = 0.076,923 076,923 ... +0.923,076 --------- 0.999,999 1/17 = 0.05882352,94117647 +0.94117647,05882352 ------------------- 0.99999999,99999999 1/19 = 0.052631578,947368421 ... +0.947368421,052631578 ---------------------- 0.999999999,999999999Ekidhikena Purvena From: Bharati Krishna Tirtha's Vedic mathematics#By one more than the one before
Concerning the number of decimal places shifted in the quotient per multiple of 1/19:
01/19 = 0.052631578,947368421 02/19 = 0.1052631578,94736842 04/19 = 0.21052631578,9473684 08/19 = 0.421052631578,947368 16/19 = 0.8421052631578,94736A factor of 2 in the numerator produces a shift of one decimal place to the right in the quotient.
In the square from 1/19, with maximum period 18 and row-and-column total of 81, both diagonals also sum to 81, and this square is therefore fully magic: 01/19 = 0·0 5 2 6 3 1 5 7 8 9 4 7 3 6 8 4 2 1... 02/19 = 0·1 0 5 2 6 3 1 5 7 8 9 4 7 3 6 8 4 2... 03/19 = 0·1 5 7 8 9 4 7 3 6 8 4 2 1 0 5 2 6 3... 04/19 = 0·2 1 0 5 2 6 3 1 5 7 8 9 4 7 3 6 8 4... 05/19 = 0·2 6 3 1 5 7 8 9 4 7 3 6 8 4 2 1 0 5... 06/19 = 0·3 1 5 7 8 9 4 7 3 6 8 4 2 1 0 5 2 6... 07/19 = 0·3 6 8 4 2 1 0 5 2 6 3 1 5 7 8 9 4 7... 08/19 = 0·4 2 1 0 5 2 6 3 1 5 7 8 9 4 7 3 6 8... 09/19 = 0·4 7 3 6 8 4 2 1 0 5 2 6 3 1 5 7 8 9... 10/19 = 0·5 2 6 3 1 5 7 8 9 4 7 3 6 8 4 2 1 0... 11/19 = 0·5 7 8 9 4 7 3 6 8 4 2 1 0 5 2 6 3 1... 12/19 = 0·6 3 1 5 7 8 9 4 7 3 6 8 4 2 1 0 5 2... 13/19 = 0·6 8 4 2 1 0 5 2 6 3 1 5 7 8 9 4 7 3... 14/19 = 0·7 3 6 8 4 2 1 0 5 2 6 3 1 5 7 8 9 4... 15/19 = 0·7 8 9 4 7 3 6 8 4 2 1 0 5 2 6 3 1 5... 16/19 = 0·8 4 2 1 0 5 2 6 3 1 5 7 8 9 4 7 3 6... 17/19 = 0·8 9 4 7 3 6 8 4 2 1 0 5 2 6 3 1 5 7... 18/19 = 0·9 4 7 3 6 8 4 2 1 0 5 2 6 3 1 5 7 8...The same phenomenon occurs with other primes in other bases, and the following table lists some of them, giving the prime, base, and magic total (derived from the formula base-1 x prime-1 / 2):
| Prime | Base | Total |
|---|---|---|
| 19 | 10 | 81 |
| 53 | 12 | 286 |
| 53 | 34 | 858 |
| 59 | 2 | 29 |
| 67 | 2 | 33 |
| 83 | 2 | 41 |
| 89 | 19 | 792 |
| 167 | 68 | 5,561 |
| 199 | 41 | 3,960 |
| 199 | 150 | 14,751 |
| 211 | 2 | 105 |
| 223 | 3 | 222 |
| 293 | 147 | 21,316 |
| 307 | 5 | 612 |
| 383 | 10 | 1,719 |
| 389 | 360 | 69,646 |
| 397 | 5 | 792 |
| 421 | 338 | 70,770 |
| 487 | 6 | 1,215 |
| 503 | 420 | 105,169 |
| 587 | 368 | 107,531 |
| 593 | 3 | 592 |
| 631 | 87 | 27,090 |
| 677 | 407 | 137,228 |
| 757 | 759 | 286,524 |
| 787 | 13 | 4,716 |
| 811 | 3 | 810 |
| 977 | 1,222 | 595,848 |
| 1,033 | 11 | 5,160 |
| 1,187 | 135 | 79,462 |
| 1,307 | 5 | 2,612 |
| 1,499 | 11 | 7,490 |
| 1,877 | 19 | 16,884 |
| 1,933 | 146 | 140,070 |
| 2,011 | 26 | 25,125 |
| 2,027 | 2 | 1,013 |
| 2,141 | 63 | 66,340 |
| 2,539 | 2 | 1,269 |
| 3,187 | 97 | 152,928 |
| 3,373 | 11 | 16,860 |
| 3,659 | 126 | 228,625 |
| 3,947 | 35 | 67,082 |
| 4,261 | 2 | 2,130 |
| 4,813 | 2 | 2,406 |
| 5,647 | 75 | 208,902 |
| 6,113 | 3 | 6,112 |
| 6,277 | 2 | 3,138 |
| 7,283 | 2 | 3,641 |
| 8,387 | 2 | 4,193 |
Famous quotes containing the words prime, reciprocal, magic and/or square:
“If Montaigne is a man in the prime of life sitting in his study on a warm morning and putting down the sum of his experience in his rich, sinewy prose, then Pascal is that same man lying awake in the small hours of the night when death seems very close and every thought is heightened by the apprehension that it may be his last.”
—Cyril Connolly (1903–1974)
“Parenting is a profoundly reciprocal process: we, the shapers of our children’s lives, are also being shaped. As we struggle to be parents, we are forced to encounter ourselves; and if we are willing to look at what is happening between us and our children, we may learn how we came to be who we are.”
—Augustus Y. Napier (20th century)
“Religion differs from magic in that it is not concerned with control or manipulation of the powers confronted. Rather it means submission to, trust in, and adoration of, what is apprehended as the divine nature of ultimate reality.”
—Joachim Wach (1898–1955)
“O for a man who is a man, and, as my neighbor says, has a bone in his back which you cannot pass your hand through! Our statistics are at fault: the population has been returned too large. How many men are there to a square thousand miles in this country? Hardly one.”
—Henry David Thoreau (1817–1862)