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In this worksheet, students learn a simple strategy for adding together 3 or more numbers.

Key stage:  KS 2

Curriculum topic:   Number: Addition, Subtraction, Multiplication and Division

Curriculum subtopic:   Perform Mental Calculations

Difficulty level:

### QUESTION 1 of 10

In this worksheet, we will learn a crafty trick to add up consecutive numbers.

Eddie has spotted that if you steal one from the last number and give it to the first number, he now has three identical numbers to add up.

For Example:

Add  together 11 + 12 + 13

Using Eddie's trick, this becomes 12 + 12 + 12 which is just 3 x 12 = 36

Eddie also notices that to add together five consecutive numbers, he can use a similar trick by stealing two from the fifth number and giving it to the first number, stealing one from the fourth number and giving it to the second number.  This gives him five identical numbers to add up.

For Example:

Add  together 6 + 7 + 8 + 9 + 10 becomes 8 + 8 + 8 + 8 + 8 which is just 5 x 8 = 40

Find the sum of these consecutive numbers

9 + 10 + 11

Find the sum of these consecutive numbers

19 + 20 + 21

Find the sum of these consecutive numbers

5 + 6 + 7 + 8 + 9

Find the sum of these consecutive numbers

10 + 11 + 12 + 13 + 14

Find the sum of these consecutive numbers

15 + 16 + 17 + 18 + 19

Use a similar method to add these numbers

20 + 30 + 40 + 50 + 60

(Hint:  Take 20 off the largest number and give it to the smallest number)

Find the sum of these consecutive numbers

5 + 6 + 7 + 8 + 9 + 10 + 11

Find the sum of these consecutive numbers

9 + 10 + 11 + 12 + 13 + 14 + 15

Find the sum of these consecutive numbers

19 + 20 + 21 + 22 + 23 + 24 + 25

Find the sum of these numbers

20 + 30 + 40 + 50 + 60 + 70 + 80

• Question 1

Find the sum of these consecutive numbers

9 + 10 + 11

30
EDDIE SAYS
Take 1 off the 11 and give it to the 9. You now have three 10s.
• Question 2

Find the sum of these consecutive numbers

19 + 20 + 21

60
• Question 3

Find the sum of these consecutive numbers

5 + 6 + 7 + 8 + 9

35
EDDIE SAYS
Take 2 off the 9 and give it to the 5. Take 1 off the 8 and give it to the 6. You now have five 7s
• Question 4

Find the sum of these consecutive numbers

10 + 11 + 12 + 13 + 14

60
• Question 5

Find the sum of these consecutive numbers

15 + 16 + 17 + 18 + 19

85
• Question 6

Use a similar method to add these numbers

20 + 30 + 40 + 50 + 60

(Hint:  Take 20 off the largest number and give it to the smallest number)

200
• Question 7

Find the sum of these consecutive numbers

5 + 6 + 7 + 8 + 9 + 10 + 11

56
• Question 8

Find the sum of these consecutive numbers

9 + 10 + 11 + 12 + 13 + 14 + 15

84
• Question 9

Find the sum of these consecutive numbers

19 + 20 + 21 + 22 + 23 + 24 + 25

154
EDDIE SAYS
7 times 22
• Question 10

Find the sum of these numbers

20 + 30 + 40 + 50 + 60 + 70 + 80

350
EDDIE SAYS
7 times 50
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