规律:第n个数就是n的平方减1
0=1^2-1
3=2^2-1
8=3^2-1
…………
990^2-1=?一会再算
所以第990个数减第989个数是2×990-1= 1979
所以第990个数应该是 0+3+5+.+1979=
(3+1979)*989/2=1982*989/2=1982*494.5=980099
观察一列数:3,8,15,24,35,48,.,依此类推第990个数是什么.
观察一列数:3,8,15,24,35,48,.,依此类推第990个数是什么.
数学人气:282 ℃时间:2019-08-20 10:06:42
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