A number pattern grows or shrinks by the same step each time. Find the step, then keep adding it to reach the next number.
The steps, on one like it
The pattern is 3, 7, 11, 15. What is the next number?
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Subtract the first number from the second: 7 - 3 = 4.
The gap between two numbers next to each other is the step.
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Check the next gap: 11 - 7 = 4.
Checking a second gap proves the step is the same every time.
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Add the step to the last number: 15 + 4.
The pattern grows by the same step, so keep adding it to go on.
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Write the answer: 19.
Fifteen plus four is nineteen, which is the next number in the pattern.
Answer: 19
The mistake people often make
Some children check only the first gap. For 2, 4, 8, 16 they add 2 each time and answer 18.
Check two gaps before you decide. If the gaps are different, look for doubling instead.
The pattern in a table
Set the pattern out in a table. The top column counts the terms 1, 2, 3, 4, 5. The next column holds the values 3, 7, 11, 15. Every time the term number goes up by 1, the value goes up by 4. Term 5 is one more step, so its value is 19.
Words to know
- term
- one number in a pattern
- step
- the amount a pattern grows or shrinks each time