Multiply by 80

Multiply a one-digit number by 80.

Try three of them

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Multiply by 80

Grade 3 · Multiplying by Multiples of 10 · question 1 of 3

0 of 12

12 rungs. A star at the top.

2 × 80 =

How it is taught

0:00 of 3:17

80 is 8 tens.

A product can sit nearer one hundred than another.

Read it: Count the groups of tens

You have 3 trays of chips. Each tray holds 4 tens. Look at those 12 chips — they are 12 tens, not 12 ones.

See each 40 as 4 tens sitting in a tray.
Multiply 3 trays by 4 tens to get 12 tens.
Write those 12 tens as 120.

Counting all 120 from 1 works, but it is slow, and a skipped chip spoils the total.

Each tray holds the same 4 tens, so 3 trays are 3 equal groups rather than a pile of 120.

12 tens is 120 because each ten is worth 10, and 12 of them sit in the tens place.

When the groups hold tens, multiply the groups by the tens, then say what those tens are worth.

Multiplying 3 by 4 and writing 12, as if the 4 tens were 4 chips.

The 12 you get are tens, so 12 tens is 120.

2 × 30 = ___ — 60. 2 × 3 = 6, and 6 tens are 60.

3 × 80

What is three times eighty?

Let's use a multiplication fact you already know: three times eight.

Three times eight equals twenty-four.

Now think of eighty as eight tens. So three times eighty means three groups of eight tens.

To find the total, we multiply three times eighty.

Three times eight is twenty-four, so three times eighty is twenty-four tens.

Twenty-four tens is the same as two hundred forty — just write a zero after twenty-four.

Three times eighty equals two hundred forty. You used a fact you already knew!

Grade 3 · Worked example: 3 × 80

What you see

While they climb, your page writes one true line to ask about tonight, and a short note each Sunday.

MayaGrade 3 · Mathematics

Did you know?

A chessboard has 64 squares — share them out between the 8 rows and each row holds exactly 8.

Today’s goal: 1 star — one skill mastered, every rung of its ladder climbed
Climbing now: Divide within 100

An example student.

MayaGrade 3 · Mathematics

Maya earned 2 stars this week — Interpret multiplication as equal groups, which took 6 answers over 3 days before its star landed 3 days ago and Multiply by 6, 7, 8 and 9. Next up: Divide within 100.

An example week.

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