✔ 最佳答案
It can sometimes happen when you round numbers.
Say x = 1.4, y = 1.4, then z = x+y = 1.4 + 1.4 = 2.8
Then if you round these numbers x = 1, y = 1, z = 3
So when looking at rounded numbers only, you may see:
x+y = z
1+1 = 3
This can sometimes happen when writing computer programs, and printing out rounded intermediate values.
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EDIT
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Here's a similar case where 1+1 = 1
x = 0.75, y = 0.6, z = x+y = 0.75+0.6 = 1.35
When rounded, you get
x + y = z
1 + 1 = 1