Calculating percentages mentally We can use percentages that

Calculating percentages mentally We can use percentages that we know to find other percentages. Suggest ways to work out: 20% 10% 35% 15% 30% 60% 1% 75% 5% 100% 15%

Recap: Percentages of Amounts Calculate the percentage of each amount as asked.

Find. . . 10% of £ 460 £ 46

Calculate. . . 20% of 180 36

Work out. . . 40% of 70 28

Find the answer to. . . 25% of 80 20

Evaluate. . . 70% of 50 35

Evaluate. . . 5% of 500 25

Find. . . 60% of 40 24

Work out. . . 80% of 90 72

Percentage Increase/Decrease • Increase £ 24 000 by 10% of 24 000 = 24 000 ÷ 10 £ 24 000 + £ 2400 Total = £ 26 400 = £ 2400

Visit each shop and work out the new price of each item Some need to be discounted Some need to be increased

£ 4 500 £ 75 £ 20 000 Multiplier £ 4 500 £ 20 000 £ 75 20% Increase 1. 2 £ 5 400 £ 24 000 £ 90

£ 8 £ 2 % d e 5 t 2 ec l cts e s off rodu p £ 9 Cost of item Cereal Variety Pack Chocolate Cake Transformers DVD £ 2 £ 8 £ 9 % Increase/ decrease 25% Decrease % Amount Multiplier (£) 0. 75 New cost of item £ 1 • 50 £ 6 • 75

% 5 tions 1 educ £ 50 r £ 60 £ 25 Clothing T-shirt Jeans Trainers Cost of item £ 25 £ 50 £ 60 % Increase/ decrease 15% Decrease % Amount Multiplier (£) 0. 85 New cost of item £ 21 • 25 £ 42 • 50 £ 51

% 0 3 £ 15 o sp r o o utd o l l a £ 30 Cost of item Cricket Set Football Gloves off ent pm i u q rts e £ 30 £ 13 £ 15 % Increase/ decrease 30% Decrease % Amount Multiplier (£) 0. 7 New cost of item £ 21 £ 9 • 10 £ 10 • 50

Utility Bill Increase Rates British Gas EDF Energy TV Licence Cost of item British Gas Bill EDF Energy Electricity Bill TV licence £ 302 • 41 £ 56 • 66 £ 116 % Increase/ decrease 5% Increase 6% Increase 5% 6% 5% % Amount Multiplier (£) 1. 05 1. 06 1. 05 New cost of item £ 317 • 53 £ 60 • 06 £ 121 • 80

Banking Interest Rates Halifax Current Account Nat. West Current Account Lloyds Current Account Halifax Savings Account Nat. West Savings Account Lloyds Savings Account £ 150 £ 740 £ 2550 Cost of item Halifax - Current Account Lloyds - Savings Account Nat. West - Current Account £ 740 £ 2550 £ 150 % Increase/ decrease 1% Increase 3% Increase 2% Increase % Amount Multiplier (£) 1. 01 1. 03 1. 02 1% 2% 0 • 5% 3% 2 • 5% 3% New cost of item £ 747 • 40 £ 2626 • 50 £ 153