计算:(12+13+14+…+199+1100)+(23+24+25+…+299+2100)+…+(9899+98100).
问题描述:
计算:(
+1 2
+1 3
+…+1 4
+1 99
)+(1 100
+2 3
+2 4
+…+2 5
+2 99
)+…+(2 100
+98 99
). 98 100
答
原式=
+(1 2
+1 3
)+(2 3
+1 4
+2 4
)+(3 4
+1 5
+2 5
+3 5
)+(4 5
+1 6
+2 6
+3 6
+4 6
)+(5 6
+1 7
+2 7
+3 7
+4 7
+5 7
)+…+(6 7
+1 100
+2 100
+3 100
+…+4 100
)98 100
=
+1+1.5+2+2.5+3+…+48.51 2
=(0.5+48.5)×97÷2
=2376.5.
答案解析:根据加法交换律、结合律,可得简便运算,可得答案.
考试点:有理数的加法.
知识点:本题考查了有理数的加法,交换律、结合律简便运算.