From 1776 -1976 there were 49 leap years.
As of and including 2012, there have been twelve leap years since 1966. Simply taking the number of elapsed years and dividing by four will only get you the correct answer part of the time, since it mathematically assumes the year before you start counting is a leap year.
The number of years between 1776 and 1976 is 200 years. You can calculate this by subtracting 1776 from 1976, which gives you 200.
200
200 of them.
A decade is 10 years, 200 years between 1776 and 1976 so the answer is 20 decades.
200 of them.
3752
36
There were 25 leap years between 1901 and 2001. They were as follows: 1904, 1908, 1912, 1916, 1920, 1924, 1928, 1932, 1936, 1940, 1944, 1948, 1952, 1956, 1960, 1964, 1968, 1972, 1976, 1980, 1984, 1988, 1992, 1996 and 2000.
Twenty decades = 200 years
There were 49 leap years between 1776 and 1976:1776, 1780, 1784, 1788, 1792, 1796, 1804, 1808, 1812, 1816, 1820, 1824, 1828, 1832, 1836, 1840, 1844, 1848, 1852, 1856, 1860, 1864, 1868, 1872, 1876, 1880, 1884, 1888, 1892, 1896, 1904, 1908, 1912, 1916, 1920, 1924, 1928, 1932, 1936, 1940, 1944, 1948, 1952, 1956, 1960, 1964, 1968, 1972, 1976.
There were 49, remembering that 1800 and 1900 were not leap years. They were: 1776, 1780, 1784, 1788, 1792, 1796, 1804, 1808, 1812, 1816, 1820, 1824, 1828, 1832, 1836, 1840, 1844, 1848, 1852, 1856, 1860, 1864, 1868, 1872, 1876, 1880, 1884, 1888, 1892, 1896, 1904, 1908, 1912, 1916, 1920, 1924, 1928, 1932, 1936, 1940, 1944, 1948, 1952, 1956, 1960, 1964, 1968, 1972 and 1976.