如何将正整数和负整数相加？
整数是整数和负数的组合。因此，数字 -3、-2、-1、0、1、2、3 称为整数。
- 自然数 1、2、3 称为正整数。
- 负数 -3、-2、-1 称为负整数。
- 数字 0 也是一个整数，但它既不是正整数也不是负整数。
数轴上整数的表示
- 画一条线并将其上的一个点标记为零。
- 选择长度单位。在 0（零）的两侧以单位长度间隔开始在线上标记点。
- 在零的右侧，将点标记为 1, 2, 3, ...，将零左侧的点标记为 -1, -2, -3, ...
- 最后，在线条的任一侧添加箭头以显示线条在两个方向上无限期地延续。
使用数轴将正整数和负整数相加
- 要添加一个正数，我们需要移动到数轴的右侧。
- 要添加负数，我们需要移动到数轴的左侧。
示例问题
问题 1：求 (-4) + 2。
解决方案：
Start from -4 on the number line. Move 2 units to the right. We reach -2.
Therefore, (-4) + 2 = -2
问题 2：求 4 + (-2)。
解决方案：
Start from 4 on the number line. Move 2 units to the left. We reach +2.
Therefore, 4 + (-2) = 2
问题 3：求 (-2) + (-1)。
解决方案：
Start from -2 on the number line. Move 1 unit to the left. We reach at -3.
Therefore, (-2) + (-1) = -3
没有数轴的正负数相加
使用数轴添加大数是一项非常繁琐的任务。还有一个更好的选择，我们有以下整数相加规则。
1. To add two positive numbers – add them as natural numbers.
2. To add two negative numbers – add their absolute values and finally give the sum a negative sign. While practising, do not consider the signs, find the sum of the numbers and give negative sign to the sum obtained.
3. To add a positive and negative number – subtract the smaller number from the larger number and give the sign of the number which is larger.
添加两个正数
示例 1：评估 (+130) + (+200)
解决方案：
As we can see here, both the numbers are positive, so we need to add them simply like natural numbers.
Therefore, (+130) + (+200) = 130 + 200 = 330.
添加两个负数
示例 2：计算 (-130) + (-200)
解决方案：
As we can see here, both the numbers are negative, so we need to add them simply as natural numbers and then give the sum a negative sign.
Therefore, (-130) + (-200) = -(130 + 200) = -330.
加一正数和一负数
示例 3：评估 (-130) + (+200)
解决方案：
As we can see here, one number is positive and another one is negativ, so we need to subtract the smaller number from the larger number and give the sign of the larger number i.e. subtract 130 from 200 and give sign as positive to the final sum.
Therefore, (-130) + (+200) = 200 – 130 = +70.