Percentage Increase and Decrease
Bar Modelling
Aim: I can use bar modelling to increase and decrease by percentages.
Section 1
Find the following percentages of the given number, using a bar model to demonstrate:
Find 25% of 456
Find 45% of 618
Find 95% of 902
Find 15% of 1093
Find 42% of 734
Find 17% of 2167
Find 98% of 592
Find 36% of 3656
Page 1 of 5
Section 2
Decrease the following numbers by the given percentage:
Decrease 472 by 25%
Decrease 508 by 30%
Decrease 1010 by 34%
Decrease 772 by 12%
Decrease 827 by 44%
Decrease 917 by 61%
Decrease 1098 by 37%
Decrease 702 by 6%
Page 2 of 5
Section 3
Increase the following numbers by the given percentage:
Increase 408 by 25%
Increase 459 by 30%
Increase 129 by 15%
Increase 782 by 45%
Increase 898 by 42%
Increase 729 by 76%
Increase 1873 by 21%
Increase 2773 by 39%
Page 3 of 5
Section 4
1. A bag of popcorn costs £1.20. A shop discounts bags of popcorn by 25%.
What is the new cost?
2. An athlete’s best time for running 400m is 50.2 seconds. After a year’s
training, the athlete cuts their time by 8%. What is their new best time?
3. A grocer normally buys 670kg of potatoes each week. One week he decides to
buy only 435.5kg. What percentage less potatoes did the grocer buy?
4. A school raises £435 for their chosen charity. In the previous year, the school
raised 18% less. How much did the school raise the previous year?
5. A shop has to increase the cost of a set of books by 20%.
The new price is £30. What was the original price?
6. A football team has an average attendance of 35 728 in one season. The following season their
average attendance increases by 32%. What is the new average attendance to the nearest
whole number?
7. A runner is training for a marathon. In week one, she runs 44 miles over
the whole week. In each of the following weeks, she increases the distance
she runs by 15%. In which week will she run more than 75 miles?
Page 4 of 5
Section 5: Challenge
A shop cut the price of a television in a sale by 20%. On a special day, they cut the sale price
by a further 25% of the sale price. What is the overall percentage discount?
Use the bar method to show your answer.
Page 5 of 5
Percentage Increase and Decrease
Bar Modelling Answers
Aim: I can use bar modelling to increase and decrease by percentages.
Section 1
Find the following percentages of the given number, using a bar model to demonstrate:
Find 25% of 456 = 114
Find 45% of 618 = 278.1
Find 95% of 902 = 856.9
Find 15% of 1093 = 163.95
Find 42% of 734 = 308.28
Find 17% of 2167 = 368.39
Find 98% of 592 = 580.16
Find 36% of 3656 = 1316.16
Section 2
Decrease the following numbers by the given percentage:
Decrease 472 by 25%
354
Decrease 508 by 30%
355.6
Decrease 1010 by 34%
666.6
Decrease 772 by 12%
679.36
Decrease 827 by 44%
463.12
Decrease 917 by 61%
357.63
Decrease 1098 by 37%
691.74
Decrease 702 by 6%
659.88
Section 3
Increase the following numbers by the given percentage:
Increase 408 by 25%
510
Increase 459 by 30%
596.7
Increase 129 by 15%
148.35
Increase 782 by 45%
1133.9
Increase 898 by 42%
1275.16
Increase 729 by 76%
1283.04
Increase 1873 by 21%
2266.33
Increase 2773 by 39%
3854.47
Section 4
1. A bag of popcorn costs £1.20. A shop discounts bags of popcorn by 25%.
What is the new cost?
90p
2. An athlete’s best time for running 400m is 50.2 seconds. After a year’s
training, the athlete cuts their time by 8%. What is their new best time?
46.184 seconds
3. A grocer normally buys 670kg of potatoes each week. One week he decides to
buy only 435.5kg. What percentage less potatoes did the grocer buy?
35%
4. A school raises £435 for their chosen charity. In the previous year, the school
raised 18% less. How much did the school raise the previous year?
£356.70
5. A shop has to increase the cost of a set of books by 20%.
The new price is £30. What was the original price?
£25
6. A football team has an average attendance of 35 728 in one season. The following season their
average attendance increases by 32%. What is the new average attendance to the nearest
whole number?
47 160.96 rounds to 47 161
7. A runner is training for a marathon. In week one, she runs 44 miles over
the whole week. In each of the following weeks, she increases the distance
she runs by 15%. In which week will she run more than 75 miles?
Week 5
Section 5: Challenge
A shop cut the price of a television in a sale by 20%. On a special day, they cut the sale price
by a further 25% of the sale price. What is the overall percentage discount?
Use the bar method to show your answer.
40% discount
25% of the sale price is 20% of the original price
20%
25%
20%
0
