Week 05 · Divide by multiplying
Wednesday
Times tens
// Missing factors, fact families and tens
⏱ about 15 min
Wednesday: Times tens
Bruce leads everyone to a stop with four big baskets.
"Each basket holds 30 pinecones," he says.
"How many pinecones are there in all?"
Bennie smiles. "Thirty is 3 tens."
"So 4 baskets hold 4 groups of 3 tens."
"That is 12 tens, and 12 tens is 120."
Bruce nods. "No need to count every pinecone!"
Learn it: multiply the tens
4 × 30 means 4 groups of 30.
30 is 3 tens. 4 × 3 tens = 12 tens.
12 tens is 120. So 4 × 30 = 120.
Each jump on this line is 30. Four jumps land on 120.
12 tens make 1 hundred and 2 tens. That is 120.
HOW MANY TENS?
- Read the question.
- Tap your answer.
4 × 30 is 4 groups of 3 tens. How many tens?
12 tens is what number?
5 × 60 is 5 groups of 6 tens. How many tens?
30 tens is what number?
MULTIPLY BY TENS
- Read the question.
- Tap your answer.
3 × 40 = ?
5 × 60 = ?
9 × 80 = ?
7 × 20 = ?
6 × 50 = ?
FIND THE MISSING FACTOR
- Read the question.
- Tap your answer.
6 × ? = 180
? × 70 = 280
8 × ? = 400
2 × ? = 140
TENS STORY PROBLEMS
- Read the question.
- Tap your answer.
Bruce sets out 8 rows of 20 stones. How many stones?
Bennie carries 3 baskets of 90 apples. How many apples?Four friends each walk 50 steps. How many steps in all?
ORDER THE PRODUCTS
- Find each product.
- Put them from least to greatest.
11st
22nd
33rd
44th
Multiply the tens, then write the number.
| Sentence | True or false? |
|---|---|
| 5 × 40 = 200 | ? |
| 3 × 60 = 18 | ? |
| 9 × 90 = 810 | ? |
| 4 × 50 = 200 | ? |
WHY THIS EXERCISE3 × 60 is 18 tens, and 18 tens is 180.
Try it
Cut paper strips and draw 10 dots on each strip.
Make 3 groups with 2 strips in each group.
Count the strips by tens. How many dots?
Make 3 groups with 2 strips in each group.
Count the strips by tens. How many dots?
Draw 3 groups of 4 tens. Write how many tens and what number.
Terrific! Tomorrow Chris tells a challenge story.