RemeliaMaths Year 4 Fractions, decimals & %
Year 4 dividing by 10 and 100
The objective: Find the effect of dividing a 1- or 2-digit number by 10 and 100; identify ones, tenths, hundredths.
The explanation, example and questions are the ones Remelia uses in the app; the questions are not taken from any test paper.
The idea
Dividing by 10 moves every digit one column to the right; dividing by 100 moves it two. The digits move; the decimal point is just the marker.
How to do it
- Dividing by 10: each digit slides one place right, so it gets ten times smaller.
- Dividing by 100: two places right.
- Fill any empty whole-number column with 0.
A worked example
45 ÷ 10 = 4.5. 45 ÷ 100 = 0.45.
Watch for
Thinking of it as "adding a decimal point". 7 ÷ 100 is 0.07 because the 7 moved two columns, past the tenths, into the hundredths.
Try four questions
-
85 ÷ 100 = ?
Show the answer to question 1
Answer: 0.85
Why:
Dividing by 100 moves every digit two places to the right. 85 ÷ 100 = 0.85.
-
In 75.32, which digit is in the tenths place?
Show the answer to question 2
Answer: 3
Why:
75.32: 7 tens, 5 ones, 3 tenths, 2 hundredths.
-
Zainab says: 91 ÷ 10 = 910.
Is Zainab right? Write the correct answer, not just yes or no.
Show the answer to question 3
Answer: 9.1 · "No, 9.1" is right too; "No" on its own scores nothing
Why:
Dividing by 10 moves every digit one place to the right. 91 ÷ 10 = 9.1.
Zainab's answer was not right: the correct answer is 9.1.
-
In 93.85, which digit is in the tenths place?
Show the answer to question 4
Answer: 8
Why:
93.85: 9 tens, 3 ones, 8 tenths, 5 hundredths.
Answers
- 1. 0.85
- 2. 3
- 3. 9.1 · "No, 9.1" is right too; "No" on its own scores nothing
- 4. 8
The mistakes Remelia names
When a wrong answer to a question like these matches one of these mistakes, the app says what the child seems to have done before they try again.
- Question 1, the answer 85: The digits have not moved. Dividing by 10 moves every digit one place to the right; dividing by 100, two places.
- Question 1, the answer 8,500: It looks as if you multiplied instead of dividing. Dividing by 10, 100 or 1,000 makes a number smaller: the digits move to the right.
- Question 1, the answer 8.5: Your digits are right, but in the wrong columns: your answer is 10 times too big.
- Question 1, the answer 0.085: Your digits are right, but in the wrong columns: your answer is 10 times too small.
- Question 2, the answer 7: That digit is in a different column. After the decimal point come tenths, then hundredths, then thousandths.