A page of the Numeropedia - the Special Encyclopedia of Numbers
[Chemistry] The atomic number of Ytterbium (Y). An element in the Lanthanide series: Lanthanum (57) to Lutetium (71).
[Geology] I-70, a major U.S. West-East interstate highway, connecting Cove Fort, Utah to Baltimore, Maryland, 2175 miles.
[Language] Prefixes : Septuage-…
[Math.] A pyramidal number (sum of all squares of integers from 1 to 24): 4900 = 12+22+…+232+242 = 702. The only pyramidal number that is a square. This is the only non-trivial solution of Watson’s equation: 12+22+…+x2 = y2.
(However, there are many formulas for solutions (n, x, y) of the equation: (n+1)2+(n+2)2+…+(n+x)2 = y2. References )
[Math.] A well-know, even complicated, formula:
arctan(1/239) = 4×arctan(1/5)–p/4 = arctan(1/70)–arctan(1/99) =
[Math.] 270 = 1,180,591,620,717,411,303,424
and 1+1+8+0+5+9+1+6+2+0+7+1+7+4+1+1+3+0+3+4+2+4 = 70.
[Math.] "Rule of 69", "Rule of 70" and "Rule of 72" are used in accounting to compute the time interval for a principal to double for a compound interest rate r. Since t = ln2/ln(1+r) = 0.693147/r, those rules state that value of t can be approximated by 0.69/r for low interest rates or more calculating-conveniently 0.70/r or 0.72/r for higher typical rates (such 5% to 10%).
[Sport] The popular scores for an even par of an 18-hole round of a golf course are 70, 71 or 72.
[Sport] The playing time of a field hockey match is 70 minutes, two 35-minute haves.
[Tech.] The “number system” code of an EAN-13 barcode for Norway’s products.
[Tech.] An average person’s eyes are approximately 70 mm (millimeters) or 2¾ inches apart. This is also the width between the side-by-side left-eye and right-eye cameras used to record 3-D movie pictures.
[Trivia] The 70th wedding anniversary is traditionally/modernly named platinum anniversary.
[Tech.] Automobile tires used in the U.S. have aspect ratio (section height/section width) is 60, 70, 75 or 80 (%).
[Trivia] U.S. freeway speed limits for automobiles are 55, 65, 70 or 75 miles/hour. The typical limit is 65 miles/hour in most states.
[World] The ISO country code for Bosnia and Herzegovina is 070. (ISO-3166)