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Math · Grade 5 Math

Chapter 1: Place Value and Decimals

Powers of Ten

A short way to write a long number.

Lesson
2
Time
About 15 minutes
0 of 8 done

Step 1: Let's Learn

Read it, or press Listen and follow the words.

10 × 10 × 10 is written 10³. The small 3 counts how many tens are multiplied.

The small raised number has a name.

Exponent says how many times a number is multiplied by itself.

Counting the zeros

10³ is 1,000, which has 3 zeros. The exponent and the zeros always match.

A warning

10³ is not 30. It is 10 multiplied three times, not 10 added three times.

What the small raised number means

10³ means 10 × 10 × 10 = 1,000. The raised number, called the exponent, counts how many tens are multiplied together — not what to multiply by. So 10⁵ is 100,000, a 1 followed by five zeros. The exponent and the zero count match for powers of ten, which is a useful coincidence but only a coincidence.

Why a shorthand is worth having

Writing 1,000,000,000 is error-prone; writing 10⁹ is not. Scientists dealing with distances between stars or the size of atoms would be lost without it. The notation also makes patterns visible: multiplying 10³ by 10² gives 10⁵, because you are simply multiplying five tens together.

Expanded form with powers

3,406 can be written (3 × 10³) + (4 × 10²) + (0 × 10¹) + (6 × 10⁰). This says exactly what place value has always said, in a notation that scales to any size of number. And 10⁰ = 1, which follows from the pattern: each step down divides by ten, and 10¹ = 10 divided by ten is 1.

Multiplying and dividing by powers of ten

Multiplying by 10² shifts every digit two places left; dividing by 10² shifts them two places right. Thinking of it as digits moving rather than zeros being added is what keeps the rule working once decimals are involved, where "add a zero" fails outright.

Step 2: Try It Yourself

Tap and try it out.

Each place up is one more power of ten.

Hundreds

1

Tens

0

Ones

0

1 hundred, 0 tens and 0 ones is 100.

Step 3: Watch an Example

One step at a time.

Watch Leo Work Out 6 × 10⁴

Leo multiplies by a power of ten.

  1. Step 1

    He reads 10⁴ as four tens multiplied together, which is 10,000.

Step 4: Your Turn

Practice makes it stick.

The Short Way

Problem 1 of 2

What is 10³ written out in full?

The Big One

Problem 2 of 2

What is 4 × 10³?

Powers and Zeros

1 of 4

What is 10² ?

2 of 4

What is 10⁵ ?

3 of 4

How many zeros does 10⁴ have?

4 of 4

Is 10³ the same as 30?

Step 5: Quick Check

Show what you know.

Question 1 of 2

What is 7 × 10² ?

Question 2 of 2

What does the exponent count?

What You Learned

  • 10³ means three tens multiplied together.
  • The exponent matches the number of zeros.
  • A power of ten is a multiplication, not a repeated addition.