Percentage increase with a multiplier

The Maths Habit

Sam says: "You can't have more than 100%."
Is Sam right?

100% = all of it+20%120%: all of it and 20% more
No. 100% is all of it. More than 100% is all of it and some more.

Increase
To make bigger.
100% = the amount+20%
Multiplier
The number you multiply by.
amount× multipliernew amount

Type it into your calculator. What does it show?

120÷100=1.2
135÷100=1.35
105÷100=1.05

Find the multiplier to increase by 20%.

100% = the amount+20%120%
100%+20%=120%
120÷100=1.2multiplier

Find the multiplier to increase by 30%.

100% = the amount+30%130%
100%+30%=130%
130÷100=1.3multiplier

Find the multiplier to increase by 20%.

100% = the amount+20%120%
100%+20%=120%
120÷100=1.2multiplier

Find the multiplier to increase by 15%.

100% = the amount+15%115%
100%+15%=115%
115÷100=1.15multiplier

Find the multiplier to increase by 20%.

100% = the amount+20%120%
100%+20%=120%
120÷100=1.2multiplier

Find the multiplier to increase by 60%.

100% = the amount+60%160%
100%+60%=160%
160÷100=1.6multiplier

Find the multiplier to increase by 20%.

100% = the amount+20%120%
100%+20%=120%
120÷100=1.2multiplier

Find the multiplier to increase by 5%.

100% = the amount+5%105%
100%+5%=105%
105÷100=1.05multiplier

Copy and complete the table.

Increase by10%40%25%70%12%2%
New percentage110%140%125%170%112%102%
Multiplier1.11.41.251.71.121.02

Why does × 1.2 increase by 20%?

100% = £50+20%120% = £60100% of £5050 × 1 = 5020% of £5050 × 0.2 = 10120% of £5050 × 1.2 = 60

Increase £60 by 20%.

100% = £60+20%120% = £72
100%+20%=120%
120÷100=1.2multiplier
60×1.2multiplier=72

Increase £80 by 15%.

100% = £80+15%115% = £92
100%+15%=115%
115÷100=1.15multiplier
80×1.15multiplier=92

Increase £60 by 20%.

100% = £60+20%120% = £72
100%+20%=120%
120÷100=1.2multiplier
60×1.2multiplier=72

Increase £30 by 40%.

100% = £30+40%140% = £42
100%+40%=140%
140÷100=1.4multiplier
30×1.4multiplier=42

Increase £60 by 20%.

100% = £60+20%120% = £72
100%+20%=120%
120÷100=1.2multiplier
60×1.2multiplier=72

Increase £200 by 5%.

100% = £200+5%105% = £210
100%+5%=105%
105÷100=1.05multiplier
200×1.05multiplier=210

Increase £60 by 20%.

100% = £60+20%120% = £72
100%+20%=120%
120÷100=1.2multiplier
60×1.2multiplier=72

A plant is 40 cm tall. It grows by 25%. How tall is it now?

100% = 40 cm+25%125% = 50 cm
100%+25%=125%
125÷100=1.25multiplier
40×1.25multiplier=50

Increase £40 by 5%. Which calculation is right?

A40 × 1.5
B40 × 1.05
C40 × 0.05
D40 + 5
A: wrote 5 after the point: 105 ÷ 100 is 1.05 (that gives £60)B: rightC: found only the 5% (£2): add it to 100% firstD: added £5, not 5%

Percentage increase with a multiplier worksheet, page 1

Percentage increase with a multiplier worksheet, page 2

Answer sheet

Is it right?
Thumbs up: right. Thumbs down: wrong.

  1. Increase 40 by 30%. 40 × 1.3 = 52

    Right

  2. Increase 20 by 5%. 20 × 1.5 = 30

    Wrong: 5% is 105%, so 1.05. The answer is 21.

  3. Increase 90 by 20%. 90 × 0.2 = 18

    Wrong: that is only the 20%. Use 1.2.

  4. Increase 90 by 10%. 90 × 1.1 = 99

    Right

  5. Increase 20 by 50%. 20 + 50 = 70

    Wrong: add 50%, not 50. The answer is 30.

  1. Increase £45 by 20%.

    £54

  2. A phone costs £250. The price goes up by 8%. What is the new price?

    £270

  3. What is the multiplier to increase by 100%? What happens to the amount?

    2. It doubles.

  4. Jo increases £80 by 10%. Then she increases the answer by 10%. Is that the same as increasing £80 by 20%?

    No. £96.80, not £96

  5. A price goes down by 20%. What is the multiplier?

    0.8 (100% − 20% = 80%)

  1. Increase £50 by 30%.

    £65
    100% = £50+30%1Addto 100%.100%30%130%+=2Divideby 100.100÷=3Multiply.×=

  2. Increase £20 by 15%.

    £23
    100% = £20+15%1Addto 100%.100%+=2Divideby 100.100÷=3Multiply.×=

  3. Increase £300 by 4%.

    £312
Exit tickets to print