Number 55

A page of the Numeropedia - the Special Encyclopedia of Numbers

[50-59]50 - 51 - 52 - 53 - 54 - 5556 - 57 - 58 - 59

20-29  30-39  40-49  50-59  60-69  70-79  80-89  90-99  100

1  - 10 - 100  - 1000 - 10,000 - 100,000 - 1M - 10M - 100M1B10B - 100B - 1T - 10T - 100T - 1Q - ...

[Biology]  Sunflower seed heads normally has 55 spirals going clockwise and 89 going counterclockwise.

[Chemistry]  The atomic number of Cesium (Cs).

[Geology]  I-55, a major U.S. North-South interstate highway, connecting Chicago, Illinois to La Place, Louisiana, 944 miles.

[Math.] A triangular number (sum of all integers from 1 to 10):

55 = 1+2+3+4+5+6+7+8+9+10.

[Math.]  A pyramidal number (sum of all squares of integers from 1 to 5): 55 = 12+22+32+42+52. The only triangular numbers whose digits are repeated are: 55, 66 and 666.

[Math.]  The 10th Fibonacci number. There are only 4 triangular numbers that are also Fibonacci numbers: 1, 3, 21 and 55.

[Math.]  510,510 = 2×3×5×7×11×13×17 (first 7 prime numbers)

= 714×715 (2 consecutive numbers)

= 13×21×34×55 (4 consecutive Fibonacci numbers).

[Math.]  (Sequence of  numbers 55 and 50…050…0)

552 = 3,025 = (30+25 )554 = 9,150,625 = (09+15+06+254

553 = 166,375 = (1+6+6+37+5)3

555 = 503,284,375 = (5+0+3+28+4+3+5+7)5

557 = 1,522,435,234,375 = (15+2+2+4+3+5+2+3+4+3+7+5)7.

[Math.]  (Sequence of numbers 49…950…0 and 50…050…0).

2025 = (20+25)2 = 452 and 3025 = (30+25)2 = 552 and 45+55 = 100.

[Math.]  13+33+33 = 55, 53+53 = 250 and 23+53+03 = 133.

[Measure]  The volume (U.S. gallons) of a traditional standard drum of oil, (208.1976 l, liters).

[Money]  A MasterCard credit card number starts with either 2 digits 51, 52, 53, 54 or 55.

[Music]  A frequency (Hz, Hertz) of the musical note A (La):

A0 = 27.5 Hz, A1 = 55 Hz, A2 = 110 Hz, A3 = 220 Hz, A4 = 440 Hz, A5 = 880 Hz, A6 = 1760 Hz,  A7 = 3520 Hz, A8 = 7040 Hz, A9 = 14,080 Hz and A10 = 28,160 Hz.

[Phone]  International telephone dialing code for Brazil.

[Phone]  The number to key in text messaging on telephone keypad for letter K.

[Phone]  The last 2 digits of an NANPA/U.S. area code cannot be the same, i.e. cannot be: 11, 22, 33, 44, 55, 66, 77, 88 or 99. (NANPA: North American Numbering Plan Administration).

[Tech.]  1 manpower = 55 ft·lb/s (feet·pound/second), exactly. Work for lifting 55 lb, one foot high in the air in one second).

[Trivia]  One of popular U.S. freeway speed limits for automobiles: 55, 65, 70 or 75 miles/hour. The typical speed limit for automobiles with trailers on most U.S. highways and interstates is 55 miles/hour.

[Zip]  The only 2 U.S. Postal Zip Codes starting with 055: Andover, Vermont 05501 and 05544. Coincidentally, the only 2 U.S. Postal Zip Codes starting with 00 are: Holtsville, New York 00501 and 00544.

[Trivia]  The 55th wedding anniversary is traditionally named emerald (or turquoise) anniversary. Modernly, it may be replaced by only emerald.