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Objectives:
• Calculate percentages using non-calculator methods.
• Calculate percentages less than 10% and values other than multiples of 10.
Vocabulary:
40 500 120 70
50 250 720 60
90 140 860 1800
20 5000 300 480
T3.1B
20 is 50% of 40. 500 is 10% of 5000
Find three more percentage relationships on the target board.
50 is 20% of 250 120 is 25% of 480 90 is 5% of 1800
70 is 50% of 140 60 is 50% of 120
120 is 40% of 300
250 is 50% of 500
90 is 75% of 120
What is 10% of £380?
How did you work out 10% of £380?
How can you use the answer for 10% to find 20%?
20% = 10% + 10% = £38 + £38 = £76
How can you use 10% to find 30%?
30% = 10% + 10% + 10% = 3 x £38 = £114
60
10%
20%
30%40%
50%
60%
On a copy of the spider diagram fill in the amounts.
W/S 3.1B
60
10%
20%
30%40%
50%
60%
6
12
1824
30
36
Answers:
How many times will 5% fit into 10%?
How can you work out 5% if you know 10%?
Find 5% of £240 – explain how you got your answer.
10% of £240 is £24 so 5% of £240 is £12.
Find 5% of £720 – explain how you got the answer.
10% of £720 is £72 so 5% of £720 is £36
0% 100%
0 £240
10%
£24
400 50 1200 700
500 24 72 600
80 140 40 1800
20 800 300 120
T3.2B
Find 5% of each amount as it is highlighted
How can you find 15% of an amount?
15% can be found by adding 10% and 5% together.
Find 15% of 300 – explain your working.
10% of 300 is 30 5% of 300 is 15 15% is 30 + 15 = 45
0% 100%
0 300
10%
30
15%
45
400 50 1200 700
500 24 72 600
80 140 40 1800
20 800 300 120
Find 15% of each number as it is highlighted.
T3.2B
60
15%25%
10%
5%
45%
55%35%
95%
17.5%
Complete a spider diagram like the one above.
W/S3.2B
60
15%25%
10%
5%
45%
55%35%
95%
17.5%
Answers
69 15
3
27
3321
57
10.5
If I can find 10% how can I find 1%?
Example: Find 1% of £350
1% is the same as 1/100th so I can divide by 100
£350 ÷ 100 = £3.5 written £3.50
1% is 10% divided by 10.
10% of £350 is £35 so 1% is £35 ÷10 = £3.5 or £3.50
Method 1
Method 2
40 500 120 70
50 250 720 60
90 140 860 1800
20 5000 300 480
State 1% of each number as it is highlighted.
T3.1B
Objectives:
• Calculate percentages using non-calculator methods.
• Calculate percentages less than 10% and values other than multiples of 10.
Vocabulary:
Thank you for your attention
