如何找到数字的百分比？
百分比被定义为某种事物的比例。它可以是数字的比例、液体的比例、物品的比例等。在数学中，它表示为百分率或1/100。百分比的使用方法在各个领域都很常见，例如税率、产品折扣百分比、空气中的湿度百分比以及混合物中物质成分的百分比。因此，计算百分比的知识有助于数学，也有助于解决日常生活中产品和许多物品的百分比值。
一个数字的百分比
百分比符号是'%. ' 也用于表示一个班级学生的平均百分比、数据表示、盈利百分比、亏损百分比、利息等。
百分比的范围在 0 到 100 之间。可以是 0.5%、10%、40%、70%、80%、92%、99%，最大可达 100%。一个数字的 100% 与该数字相同。
例如，
100 percentages of 10 means
100% of 10
100 × 1/100 × 10
= 10
Hence proved, that 100% of a number is the same as the number itself.
注：百分比等于数字除以 100
例如，
20%
20 % = 20/100
Thus, 20% is represented as a fraction of 20/100.
假设要计算一个数 N 的百分比，它将表示为：
P% of N
P/100 × N
Or
(P × N)/100
Where,
P is the percent
N is the number
% is equal to 1/100
例如，
10% of 20
It is equal to 2
Thus, to find the percentage value of a number, we need to simply multiply the number with the percentage value and divide it by 100.
求数字百分比的步骤
Let’s consider an example to find 10% of 500.
Step 1: Substitute 1/100 instead of the % symbol
10 × 1/100 of 500
Step 2: Substitute multiply symbol (×) instead of ‘of’
10 × 1/100 × 500
Step 3: Solve the above-formed equation
10 × 500/100
5000/100
= 50
Thus, 10% of 500 is 50.
增加一个数字的百分比
Let’s consider an example.
10% increase of the number 50
The formula is given by:
Number + percentage of the same number
50 + 10% of 50
= 50 + 10 × 1/100× 50
= 50 + 500/100
= 50 + 5
= 55
查找数字百分比增加的步骤
Example: Find15% increase of 200.
Step 1: Form an equation using the formula
The formula is given by:
Number + percentage of the same number
= 200 + 15% of 200
Step 2: Substitute 1/100 instead of the % symbol
15× 1/100 of 200
Step 3: Substitute multiply symbol (×) instead of ‘of’
15 × 1/100 × 200
Step 4: Solve the above-formed equation
15× 200/100
3000/100
= 30
Step 4: Add the number
200 + 30
= 230
Thus, a 15% increase of 200 is 230.
Direct formula
(100 + increase percentage value)% × number
(100 + 15)% × 200
(115)% × 200
115 × 1/100 × 200
= 230
减少数字的百分比
Let’s consider an example.
10% decrease of the number 50
The formula is given by:
Number – the percentage of the same number
50 – 10% of 50
= 50 – 10 × 1/100 × 50
= 50 – 500/100
= 50 – 5
= 45
查找数字百分比增加的步骤
Example: Find a 45% decrease of 300.
Step 1: Form an equation using the formula
The formula is given by:
Number – the percentage of the same number
= 300 – 45% of 300
Step 2: Substitute 1/100 instead of the % symbol
45× 1/100 of 300
Step 3: Substitute multiply symbol (×) instead of ‘of’
45 × 1/100 × 300
Step 4: Solve the above-formed equation
45× 300/100
135000/100
= 135
Step 5: Subtract the number
300 – 135
= 165
Thus, a 45% decrease of 300 is 165.
Direct formula
(100 – decrease percentage value)% × number
(100 – 45)% × 300
(55)% × 300
55 ×1/100 × 300
= 165
示例问题
问题 1：找到 80 的 20%？
解决方案：
20 × 1/100 × 80
= (20 × 80)/100
= 1600/100
16
Thus, 20% of 80 equals to 16.
问题 2：找到 200 的 50%？
解决方案：
50 × 1/100 × 200
= (50 × 200)/100
= 10000/100
= 100
Or
50/100 × 200
= (1/2) × 200
= 0.5 × 200
= 100
Thus, 50% of 200 equals to 100.
问题 3：找到 50 的 10%？
解决方案：
10 × 1/100 × 50
= (10 × 50)/100
= 500/100
= 5
Thus, 10% of 50 equals to 5.
问题 4：找到 5 的 0.5%？
解决方案：
0.5 × 1/100 × 5
= (0.5 × 5)/100
= 2.5/100
= 0.025
Thus, 0.5% of 5 equals to 0.025.
问题 5：找到 600 的 80%？
解决方案：
80 × 1/100 × 600
= (80 × 600)/100
= 48000/100
= 480
Thus, 80% of 600 equals to 480.
问题 6：求 22% 增加 50。
解决方案：
The formula to find the percentage increase of a number is given by:
(100 + increase percentage value)% × number
(100 + 22)% × 50
(122)% × 50
122 × 1/100 × 50
= 61
问题 7：求 150 减少 70%。
解决方案：
The formula to find the percentage decrease of a number is given by:
(100 – decrease percentage value)% × number
(100 – 70)% × 150
(30)% × 150
30 × 1/100 × 150
= 45