Grade 3Math
Multiplying Tens and HundredsThink in groups of 10 and 100
For multiplication like 20 × 4 and 200 × 4, if you think about how many 10s or 100s there are, you can calculate with the times tables.
The narration and the pictures are in Japanese. You can hear the same words that are used in class at a Japanese school.
- Video
- 1:18（6 scenes）
- Problems
- 2 problems
Open this lesson in Japanese（何十・何百の かけ算）
Let's try
Write the math sentence in your notebook first, then open the answer.
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1What is 30 × 4?
Hint
How many 10s are in 30? Use the times tables to think about how many 10s there are in all.
Answer
It is 120. 30 is 3 10s. 3 × 4 = 12, so it is 12 10s, which is 120.
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2What is 500 × 3?
Hint
How many 100s are in 500? Think about how many 100s there are in all.
Answer
It is 1500. 500 is 5 100s. 5 × 3 = 15, so it is 15 100s, which is 1500.
Words in this lesson
- tens (a number of tens) 何十
- A number made of some 10s put together (20, 30, 40, and so on).
- hundreds (a number of hundreds) 何百
- A number made of some 100s put together (200, 300, 400, and so on).
- how many groups いくつ分
- A way of saying how many groups of the same number there are.
For parents and guardians
- The names of lessons and the order of topics differ slightly between textbooks. This page follows the content of Japan's national curriculum guidelines (the Course of Study).
- If your child only memorizes "add a 0 to the times table answer," the reason gets lost. Please check by starting from lining up 10-yen or 100-yen coins and counting "how many 10s" and "how many 100s."
- The way of thinking of a 2-digit number as tens and ones is the basis for the column method of multiplication learned next. The column method is covered in "Multiplication in Columns."