题库搜索>问题求解PS-13349
In the first week of the year, Nancy saved $1. In each of the next 51 weeks, she saved $1 more than she had saved in the previous week. What was the total amount that Nancy saved during the 52 weeks?
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暂无雷哥网文字解析
第一周：1刀
第二周：1刀+1刀
第三周：1刀+1刀+1刀
所以低52周要存：52刀
所以这52周总共存的钱应该是：1+2+3+.....+52=（n(n+1)）/2=1378
借我借我一双慧眼吧
一定要记好数列求和公式：n个数相加=（n（n+1））/2
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2015-12-08 11:35:01
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