Number Sequence to 20

Kindergarten · mathematics · 96 practice problems · read aloud

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Number Sequence to 20

🧠 What is a Number Sequence?

A number sequence is a line-up of numbers in the right order, like 1, 2, 3, 4... all the way to 20! It's like counting how many toys you have or how many steps you take. Knowing this order helps us count, add, and understand numbers.

🚀 How to Count to 20

  1. Start at 1: Point to the first number and say "one."
  2. Go Forward: Move your finger to the next number and say the next word: "two," "three," "four"...
  3. Keep Going! Don't stop! Continue all the way until you reach 20.
  4. Practice: Say the numbers out loud. Try counting your crayons or snacks!

📚 Let's Look at Examples

Example 1: What comes after 7?

Let's count: ...5, 6, 7, 8! The number that comes after 7 is 8.

Example 2: Fill in the missing number: 11, 12, ?, 14

We know 11, 12... the next number is 13, then 14. The missing number is 13.

⚠️ Common Mistakes to Avoid

  • Skipping the "Teen" Numbers: It's easy to mix up numbers like 13 (thir-teen) and 30 (thir-ty). Go slow with 13, 14, 15...
  • Getting Stuck After 10: Remember, after 10 comes 11, not 20! Practice the "teen" numbers.
  • Rushing: Saying numbers too fast can make you skip one. Point to each number as you say it.

💡 Tips & Tricks

  • Sing a Song! There are many fun counting songs that make learning the sequence easy.
  • Use a Number Line: A picture with numbers in order can help you see what comes next.
  • Teen Number Trick: Numbers 13-19 all start with "teen." Think "thir-teen," "four-teen," "fif-teen."

🎯 How to Practice

  • Count everything! Count stairs, buttons, and pieces of fruit.
  • Ask a grown-up to hide a number. Can you guess which one is missing?
  • Write the numbers 1-20 on pieces of paper and put them in order on the floor.

Practice problems

6 of the 96, worked through step by step — try them before opening the answer.

1 5, 10, _, 20

Hint: Think about counting by fives. Say the numbers out loud and listen for the pattern.

Show the answer

Answer: 15

  1. Look at the sequence: 5, 10, _, 20.
  2. Count by fives: 5, 10, 15, 20.
  3. The missing number is 15.

The answer is 15.

2 12, 13, _, 15

Hint: Look at the numbers before and after the blank to find the pattern

Show the answer

Answer: 14

  1. Look at the sequence: 12, 13, _, 15
  2. Notice that 12 comes before 13, so the numbers are increasing
  3. 13 is one more than 12, so the pattern is counting up by ones
  4. After 13 comes 14, then 15
  5. The missing number is 14

The answer is 14.

3 1, 3, _, 7, 9

Hint: Look at the numbers and think about counting by twos. What number comes between 3 and 7 when you skip every other number?

Show the answer

Answer: 5

  1. Look at the sequence: 1, 3, _, 7, 9.
  2. Notice that each number goes up by 2: 1 + 2 = 3, 3 + 2 = 5, 5 + 2 = 7, 7 + 2 = 9.
  3. The missing number is 5.

The answer is 5.

4 17, 18, _, 20

Hint: Say the numbers in order. What number comes after 18 and before 20?

Show the answer

Answer: 19

  1. Look at the sequence: 17, 18, _, 20.
  2. Count forward from 17: 17, 18, 19, 20.
  3. The missing number is 19.

The answer is 19.

5 2, _, 4, 5, 6

Hint: Say the numbers in order from 2 up to 6. Listen for the number that fits in the empty spot.

Show the answer

Answer: 3

  1. Look at the sequence: 2, _, 4, 5, 6.
  2. Count forward from 2: 2, 3, 4, 5, 6.
  3. The missing number between 2 and 4 is 3.

The answer is 3.

6 2, 4, _, 8, 10

Hint: Look at how the numbers change as you move from left to right. What pattern do you see?

Show the answer

Answer: 6

  1. Look at the sequence: 2, 4, _, 8, 10.
  2. Count forward by 2s: 2, 4, 6, 8, 10.
  3. The missing number is 6.

The answer is 6.

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