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In this activity, we will learn to identify the missing numbers in a given sequence.
Look at this sequence.
| 15 | 18 | 21 | 24 | 27 | 30 | 33 |
It goes up in steps of 3.
So, the rule for this sequence is 'add 3'.
Let's look at another sequence. This time some numbers are missing.
| A | 22 | 29 | 36 | 43 | B | C |
To find the missing numbers, we first work out the differences between the existing numbers in the sequence.
The difference between 22 and 29 is 7.
29 - 22 = 7
The difference between 36 and 43 is also 7.
43 - 36 = 7
So, we know the numbers in this sequence go up in 7s.
We can find the first missing number by counting back 7 from 22.
22 - 7 = 15
Then, we can find the second and third missing numbers by counting on in steps of 7.
43 + 7 = 50
50 + 7 = 57
The missing numbers are 15, 50 and 57.
| 15 | 22 | 29 | 36 | 43 | 50 | 57 |
Now let's try an example.
Example:
Find the missing numbers in the sequence.
| A | 17 | 22 | 27 | 32 | B | C |
Answer:
22 - 7 = 5
27 - 22 = 5
32 - 27 = 5
This sequence is counting in 5s.
So the first missing number is 17 - 5 = 12.
The last two numbers are 37 and 42.
| 12 | 17 | 22 | 27 | 32 | 37 | 42 |
Now it's your turn to work out some missing numbers in sequences.
