Tag Archives: Reversals

Reversals | Products : a * bcd = d * cba

(1) Consider a 4-digit integer   abcd   and its reversal   dcba and the products: a   *   bcd   =   d   *   cba   For example, 2   *   819   =   … Continue reading

Multiples of 7 and their reversals — Part 1

Multiples of 7 under 1000: 7, 14, 21, 28, 35, 42, 49, 56, 63, 70, 77, 84, 91, 98, 105, 112, 119, 126, 133, 140, 147, 154, 161, 168, 175, 182, 189, 196, 203, 210, 217, 224, 231, 238, 245, … Continue reading

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Temperatures – Numbers and their reverses

16   Celsius is approximately   61   Fahrenheit and 28   Celsius ~   82   Fahrenheit. Any others?

Num3er 2178

2178   =   2 * 3^2 * 11^2 2178   has a representation as a sum of 2 squares: 2178   =   33^2   +   33^2   2178   reverses itself: 2178 * 4   =   … Continue reading

Conjecture | Products of Integers & their Reversals: 1089

1089 = 33^2 is a perfect square. 9801 = 99^2 is a perfect square. 1089 * 9801 = 10673289 = 3^6 * 11^4 = 3267^2 is a perfect square. 144 = 12^2 441 = 21^2 144 * 441 = 63504 … Continue reading

When Num3er multiplied by its reversal is a perfect square

(1)   13 * 31 = 403,   169 = 13^2   &   961 = 31^2 169 * 961 = 162409 = 403^2 Inserting 0s, 10609 * 90601 = 961186009 = 31003^2 1006009 * 9006001 = 9060118060009 = 3010003^2 … Continue reading

Dates & Reversals on the Same Day of the Week For April

Older post: Dates & Reversals on the Same Day of the Week For Jan., Feb. & March For example Today’s date is :    Sunday, March 11, 2012 So I write:    11/03/2012 … Sun The reversal of   11/03/2012 … Continue reading

Dates & Reversals on the Same Day of the Week For Jan., Feb. & March [PART ONE]

I used the “dd-mm-yyyy” format and this search engine:Day of Week Calculator Today’s date is: Sunday, March 04, 2012 So I write: 04/03/2012 … Sun The reversal of 04/03/2012 is 21/02/3040 which will occur on a Friday. They don’t share … Continue reading

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4-digit Num3ers & Reversals

8712 is an integral multiple of its reversal, 2178, as 8712 = 4 * 2178 Question: Find another 4-digit number which is a non-trivial integral multiple of its reversal.

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Interesting Num3ers & their reversals

91 & 19 19 is a prime number              91 = 7 * 13 91^2 = 8281 (a square formed by concatenation of 2 consecutive numbers: 8281 = 82 || 81 8 + 2 + 81 = 91                     … Continue reading

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