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Counting Patterns within 1000
Consider the number pattern given below:
| 11 | 13 | 15 | ? | 19 | 21 |
Let's identify the missing number.
Notice that the numbers are increasing.
To find the missing number, let’s find the rule first.
Observe that:
11 + 2 = 13
13 + 2 = 15
So, the rule is “Count forward by 2”.
11 + 2 = 13
13 + 2 = 15
15 + 2 = 17
17 + 2 = 19
19 + 2 = 21
So, the missing number is 17.
