How to Work out Percentage Increases (1% Method and Decimal Multiplier Method).
If you are carrying out a percentage increase question then you are making the amount larger by a given percentage. Here are two methods that you can use to work out a percentage increase question. The second method is quicker than the first, and can be used on harder percentage question over a repeated amount of years.
Method 1 (1% Method).
1. Work out 1% of your number. Do this by dividing the amount by 100
2. Multiply this amount by your percentage.
3. Add this amount back onto the original amount.
Method 2 (Decimal Multipier Method).
1. Add the percentage to 100.
2. Change the percentage to a decimal (by dividing by 100).
3. Multiply the amount by this decimal.
Both methods will give exactly the same answer. The second method is a quicker method and it can be applied to harder percentage questions.
Example 1
Increase 62m by 18%
Method 1
1. Work out 1% of your number. Do this by dividing the amount by 100
1% = 0.62 ( 62 ÷ 100 = 0.62)
2. Multiply this amount by your percentage.
0.62 × 18 = 11.16
3. Add this amount back onto the original amount.
62 + 11.16 = 73.16m
Method 2
1. Add the percentage to 100.
100 + 18 = 118%
2. Change the percentage to a decimal (by dividing by 100).
118% = 1.18 (divide by 100)
3. Multiply the amount by this decimal.
62 × 1.18 = 73.16m
Example 2
A bank account contains £2000. If the interest rate is 3.7%, how much money will be in the account at the end of the year?
Method 1
1. Work out 1% of your number. Do this by dividing the amount by 100
1% = £20 ( 2000 ÷ 100 = 20)
2. Multiply this amount by your percentage.
20 × 3.7 = £74
3. Add this amount back onto the original amount.
2000 + 74 = £2074
Method 2
1. Add the percentage to 100.
100 + 3.7 = 103.7%
2. Change the percentage to a decimal (by dividing by 100).
103.7% = 1.037 (divide by 100)
3. Multiply the amount by this decimal.
2000 × 1.037 = £2074
So you can see that both methods give a final answer of £2074 in the bank account at the ned of the year.
Example 3
A tree is 4m tall. Over the next year it grows by 27%. How tall is the tree now?
Method 1
1. Work out 1% of your number. Do this by dividing the amount by 100
1% = 0.04 (4 ÷ 100 = 0.04)
2. Multiply this amount by your percentage.
0.04 × 27 = 1.08
3. Add this amount back onto the original amount.
4 + 1.08 = 5.08m
Method 2
1. Add the percentage to 100.
100 + 27 = 127%
2. Change the percentage to a decimal (by dividing by 100).
127% = 1.27 (divide by 100)
3. Multiply the amount by this decimal.
4 × 1.27 = 5.08m
So the tree is 5.08m tall.
Check out this link below to find some more questions but on percentage decreases.
Percentage Decrease Problems. 2 Easy Ways To Decrease An amount By A Percentage..
