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Math · Grade 1 Math

Chapter 4: Teen Numbers and the Unit of Ten

Writing Teen Numbers

The tens digit always comes first.

Lesson
4
Time
About 11 minutes
0 of 6 done

Step 1: Let's Learn

Read it, or press Listen and follow the words.

In 14, the 1 means one ten. The 4 means four ones.

Writing 41 would be a different number. The order matters.

Position carries meaning

In 15 the 1 does not mean one. It means one ten. Where a digit sits tells you what it is worth.

Why tens go first

We write the biggest part first, the way we say hundreds before tens. Keeping that order is what makes numbers comparable at a glance.

Step 2: Try It Yourself

Tap and try it out.

Change the number. Watch which digit is the tens and which is the ones.

Tens

1

Ones

5

1 ten and 5 ones is 15. Say it as "ten five".

Step 3: Watch an Example

One step at a time.

Watch Leo Write It Down

Leo has one ten and 3 ones.

  1. Step 1

    He writes the tens digit first: 1.

Step 4: Your Turn

Practice makes it stick.

Writing It Down

Problem 1 of 1

One ten and 9 ones. What number do you write?

Which Number?

Tens first, then ones.

1 of 3

One ten and 1 one is which number?

2 of 3

One ten and 0 ones is which number?

3 of 3

Two tens and 0 ones is which number?

Step 5: Quick Check

Show what you know.

Question 1 of 2

In 16, how many ones are there?

Question 2 of 2

One ten and 2 ones is which number?

What You Learned

  • The first digit is the tens.
  • The second digit is the ones.
  • 13 and 31 are different numbers.