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Primary Maths · Year 5Chapter 5 · Division
Year 5 · Short Division and Remainders · Lesson 5.1

Year 5: Dividing by 10, 100 and 1,000

Part of the Year 5 short division and remainders chapter. Chapter overview · whole chapter on one page · Download worksheet (PDF) · Answers (PDF)

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5.1

Dividing by 10, 100 and 1,000

Year 5
Divide whole numbers and numbers with decimals by 10, 100 and 1,000, Place value and place holders, Convert between metric units

When you divide by 10, every digit becomes 10 times smaller. A 3 in the hundreds column (300) becomes a 3 in the tens column (30). So every digit moves one place to the right. Dividing by 100 moves every digit two places to the right, and dividing by 1,000 moves every digit three places to the right. This is the opposite of multiplying by 10, 100 or 1,000 in Chapter 4.

HTOt360360÷ 10
360 ÷ 10 = 36. The 3 moves from the hundreds to the tens, the 6 from the tens to the ones. The 0 moves to the tenths and is not needed, so we do not write it.

The decimal point does not move. It is the digits that move. When a digit moves across the point it becomes a tenth, a hundredth or a thousandth. For example 4 ones become 4 tenths, so 4 ÷ 10 = 0.4. And 4.7 ÷ 10 = 0.47, because the 4 ones become 4 tenths and the 7 tenths become 7 hundredths.

Oth47047÷ 10
4.7 ÷ 10 = 0.47. The ones column is now empty, so we write a 0 there (orange). It is a place holder, and it keeps the point easy to see.

Dividing by 1,000 moves the digits three places. For example 35 ÷ 1,000 = 0.035. The ones and the tenths are empty, so we fill them with zeros. This idea is used to change units: 1 kg = 1,000 g, so to change grams into kilograms you divide by 1,000. In the same way 100 cm = 1 m and 100p = £1.

TOthth350035÷ 1,000
35 ÷ 1,000 = 0.035. Both the 3 and the 5 move three places to the right. The two empty places (ones and tenths) get zeros.

Key ideas

  • Dividing by 10 moves every digit 1 place to the right; by 100, 2 places; by 1,000, 3 places.
  • Fill any empty places with zeros (place holders). Write the 0 in the ones column: 0.47, not .47.
  • The decimal point does not move. The digits move.
  • Dividing makes a number smaller. If your answer is bigger, the digits moved the wrong way.
  • To change to a bigger unit, divide: g → kg (÷ 1,000), cm → m (÷ 100), m → km (÷ 1,000), p → £ (÷ 100).
Worked example 5.1.1
Work out 340 ÷ 10.

Key words. Place value tells you what each digit is worth. A place holder is a zero that keeps the other digits in the right columns. Dividing by 10, 100 or 1,000 makes a number 10, 100 or 1,000 times smaller.

Method. To divide by 10, move every digit 1 place to the right. The decimal point does not move. Fill empty places with zeros.

  1. Say what dividing by 10 does. Each digit becomes 10 times smaller, so it moves 1 place to the right. The digits move. The decimal point does not.
    3 hundreds become 3 tens
    4 tens become 4 ones
  2. Move every digit 1 place to the right. Use a place-value chart and follow the arrows.
    HTOt340340÷ 10
  3. Look at the zeros at the end. Zeros at the very end of a decimal do not change its value, so we do not write them.
    340 ÷ 10 = 34
  4. Write the answer.
    340 ÷ 10 = 34

Check. Go back: 34 × 10 = 340 (the digits move 1 place to the left). ✓

Watch out. Taking off zeros works here because 340 ends in 1 zero. It does not work for every number: 47 ÷ 10 is 4.7, not 4.

Worked example 5.1.2
Work out 6,500 ÷ 100.

Key words. Place value tells you what each digit is worth. A place holder is a zero that keeps the other digits in the right columns. Dividing by 10, 100 or 1,000 makes a number 10, 100 or 1,000 times smaller.

Method. To divide by 100, move every digit 2 places to the right. The decimal point does not move. Fill empty places with zeros.

  1. Say what dividing by 100 does. Each digit becomes 100 times smaller, so it moves 2 places to the right. The digits move. The decimal point does not.
    6 thousands become 6 tens
    5 hundreds become 5 ones
  2. Move every digit 2 places to the right. Use a place-value chart and follow the arrows.
    ThHTOth65006500÷ 100
  3. Look at the zeros at the end. Zeros at the very end of a decimal do not change its value, so we do not write them.
    6,500 ÷ 100 = 65
  4. Write the answer.
    6,500 ÷ 100 = 65

Check. Go back: 65 × 100 = 6,500 (the digits move 2 places to the left). ✓

Watch out. Taking off zeros works here because 6,500 ends in 2 zeros. It does not work for every number: 47 ÷ 10 is 4.7, not 4.

Worked example 5.1.3
Work out 47 ÷ 10.

Key words. Place value tells you what each digit is worth. A place holder is a zero that keeps the other digits in the right columns. Dividing by 10, 100 or 1,000 makes a number 10, 100 or 1,000 times smaller.

Method. To divide by 10, move every digit 1 place to the right. The decimal point does not move. Fill empty places with zeros.

  1. Say what dividing by 10 does. Each digit becomes 10 times smaller, so it moves 1 place to the right. The digits move. The decimal point does not.
    4 tens become 4 ones
    7 ones become 7 tenths
  2. Move every digit 1 place to the right. Use a place-value chart and follow the arrows.
    TOt4747÷ 10
  3. Keep the decimal point between the ones and the tenths. The point stays still, so the digits that moved across it are now in the decimal columns.
    47 ÷ 10 = 4.7
  4. Write the answer.
    47 ÷ 10 = 4.7

Check. Go back: 4.7 × 10 = 47 (the digits move 1 place to the left). ✓

Watch out. The answer has a decimal point because 47 does not end in enough zeros. The point goes between the ones and the tenths.

Worked example 5.1.4
Work out 4.7 ÷ 10.

Key words. Place value tells you what each digit is worth. A place holder is a zero that keeps the other digits in the right columns. Dividing by 10, 100 or 1,000 makes a number 10, 100 or 1,000 times smaller.

Method. To divide by 10, move every digit 1 place to the right. The decimal point does not move. Fill empty places with zeros.

  1. Say what dividing by 10 does. Each digit becomes 10 times smaller, so it moves 1 place to the right. The digits move. The decimal point does not.
    4 ones become 4 tenths
    7 tenths become 7 hundredths
  2. Move every digit 1 place to the right. Use a place-value chart and follow the arrows.
    Oth47047÷ 10
  3. Fill the empty places with zeros. The ones column is empty. A zero in it is a place holder: it keeps every digit in its right column.
    4.7 ÷ 10 = 0.47
  4. Write the answer.
    4.7 ÷ 10 = 0.47

Check. Go back: 0.47 × 10 = 4.7 (the digits move 1 place to the left). ✓

Watch out. Dividing makes a number smaller. Do not forget the zero in the ones column: write 0.47, not .47.

Worked example 5.1.5
Work out 35 ÷ 1,000.

Key words. Place value tells you what each digit is worth. A place holder is a zero that keeps the other digits in the right columns. Dividing by 10, 100 or 1,000 makes a number 10, 100 or 1,000 times smaller.

Method. To divide by 1,000, move every digit 3 places to the right. The decimal point does not move. Fill empty places with zeros.

  1. Say what dividing by 1,000 does. Each digit becomes 1,000 times smaller, so it moves 3 places to the right. The digits move. The decimal point does not.
    3 tens become 3 hundredths
    5 ones become 5 thousandths
  2. Move every digit 3 places to the right. Use a place-value chart and follow the arrows.
    TOthth350035÷ 1,000
  3. Fill the empty places with zeros. The ones and tenths columns are empty. A zero in each is a place holder: it keeps every digit in its right column.
    35 ÷ 1,000 = 0.035
  4. Write the answer.
    35 ÷ 1,000 = 0.035

Check. Go back: 0.035 × 1,000 = 35 (the digits move 3 places to the left). ✓

Watch out. Dividing makes a number smaller. Do not forget the zero in the ones column: write 0.035, not .035.

Worked example 5.1.6
Find the missing number.   6.3 ÷ ? = 0.063

Key words. Place value tells you what each digit is worth. A place holder is a zero that keeps the other digits in the right columns. Dividing by 10, 100 or 1,000 makes a number 10, 100 or 1,000 times smaller.

Method. Find out how far the digits move. One place to the right is ÷ 10, two places is ÷ 100 and three places is ÷ 1,000.

  1. Compare the two numbers. Look at how the digits have moved from the start number to the answer.
    6.3 → 0.063
  2. Count how many places the digits moved. Each digit moved to the right, so the number got smaller.
    Othth630063÷ 100
  3. Say what the number is. Digits that move 2 places to the right mean ÷ 100.
    6.3 ÷ 100 = 0.063

Check. 6.3 ÷ 100 = 0.063. ✓

Watch out. Put your answer back in the box and read the whole sentence. It must be true.

Worked example 5.1.7
A bag of flour has a mass of 2,400 g. How many kilograms is that?

Key words. Place value tells you what each digit is worth. A place holder is a zero that keeps the other digits in the right columns. Dividing by 10, 100 or 1,000 makes a number 10, 100 or 1,000 times smaller.

Method. Changing g into kg makes the number smaller (the new unit is bigger), so divide by 1,000.

  1. Decide what to do. 1 kg = 1,000 g, so there are 1,000 times as many g as kg. Dividing makes the number smaller.
    2,400 g ÷ 1,000
  2. Say what dividing by 1,000 does. Each digit becomes 1,000 times smaller, so it moves 3 places to the right. The digits move. The decimal point does not.
    2 thousands become 2 ones
    4 hundreds become 4 tenths
  3. Move every digit 3 places to the right. Use a place-value chart and follow the arrows.
    ThHTOthth24002400÷ 1,000
  4. Look at the zeros at the end. Zeros at the very end of a decimal do not change its value, so we do not write them.
    2,400 ÷ 1,000 = 2.4
  5. Write the answer with its unit.
    2.4 kg

Check. Go back: 2.4 × 1,000 = 2,400 (the digits move 3 places to the left). ✓

Watch out. Check the units: a bigger unit means a smaller number. The kg are the bigger unit.

Worked example 5.1.8
A pack of 100 pencils costs £37. How many pence does one pencil cost?

Key words. Place value tells you what each digit is worth. A place holder is a zero that keeps the other digits in the right columns. Dividing by 10, 100 or 1,000 makes a number 10, 100 or 1,000 times smaller.

Method. Draw a bar model, choose the operation, then work it out.

  1. Draw a bar model. 100 equal parts: one for each pencil.
    3,700p???· · ·?
  2. Choose the operation. 100 pencils cost 3,700p, so one pencil costs the total divided by 100.
    3,700p ÷ 100
  3. Say what dividing by 100 does. Each digit becomes 100 times smaller, so it moves 2 places to the right. The digits move. The decimal point does not.
    3 thousands become 3 tens
    7 hundreds become 7 ones
  4. Look at the zeros at the end. Zeros at the very end of a decimal do not change its value, so we do not write them.
    3,700 ÷ 100 = 37
  5. Write the answer. Include the unit.
    37p

Check. Go back: 37 × 100 = 3,700 (the digits move 2 places to the left). ✓

Watch out. Taking off zeros works here because 3,700 ends in 2 zeros. It does not work for every number: 47 ÷ 10 is 4.7, not 4.

Watch out

Do not say “take off a zero”. That only works when the number ends in zeros: 450 ÷ 10 = 45, but 47 ÷ 10 = 4.7, not 4. Also remember dividing makes the number smaller: 6.4 ÷ 10 is 0.64, not 6.04 and not 64. The digits all move, including the 6.

Exercise 5A  Dividing by 10, 100 and 1,000

Non-calculator
1
FWork out each division by 10.
(a)70 ÷ 10 =
(b)250 ÷ 10 =
(c)1,300 ÷ 10 =
(d)8,060 ÷ 10 =
2
FWork out each division by 100.
(a)800 ÷ 100 =
(b)4,500 ÷ 100 =
(c)36,000 ÷ 100 =
(d)7,300 ÷ 100 =
3
FWork out each division by 1,000.
(a)9,000 ÷ 1,000 =
(b)42,000 ÷ 1,000 =
(c)6,500 ÷ 1,000 =
(d)780 ÷ 1,000 =
4
FQuick-fire! Work out each answer.
(a)540 ÷ 10 =
(b)540 ÷ 100 =
(c)540 ÷ 1,000 =
(d)7 ÷ 10 =
(e)2,300 ÷ 100 =
(f)91 ÷ 100 =
5
FDivide each decimal by 10.
(a)3.6 ÷ 10 =
(b)0.7 ÷ 10 =
(c)12.4 ÷ 10 =
(d)0.05 ÷ 10 =
(e)8.25 ÷ 10 =
6
FDivide each number by 100 or by 1,000.
(a)2.4 ÷ 100 =
(b)38 ÷ 100 =
(c)7.05 ÷ 100 =
(d)9 ÷ 1,000 =
(e)347.2 ÷ 1,000 =
(f)62 ÷ 1,000 =
7
FFind each missing number.
(a)4.5 ÷ ? = 0.045
(b)? ÷ 10 = 3.6
(c)70 ÷ ? = 0.07
(d)? ÷ 100 = 0.029
(e)63 ÷ ? = 6.3
(f)? ÷ 1,000 = 0.804
8
FLook at each place-value chart.
(a)
HTOth235???÷ 100
What is the answer?
(b)
TOt1818÷ ?
What did the digits move by? What is the number you divided by?
9
FChange each measurement to the bigger unit.
(a)3,500 m = ? km
(b)450 cm = ? m
(c)2,750 g = ? kg
(d)825 ml = ? litres
(e)365p = £ ?
10
PSA pack of 100 stickers costs £37. How many pence does one sticker cost?
11
PSA bakery makes 3,000 rolls. The rolls are put into packs of 10. How many packs are there?
12
RNoah says, “6.4 ÷ 10 = 6.04.” What has Noah done wrong? What is the correct answer?
13
RAlways, sometimes or never?
(a)When you divide a number by 100, every digit moves 2 places to the right.
(b)When you divide a whole number by 10, the answer is a whole number.
14
RWhich is the odd one out? Explain how you know.    4,800 ÷ 100   480 ÷ 10   48,000 ÷ 1,000   4,800 ÷ 10
15
RChallenge! Find the missing number.   6.3 ÷ ? = 0.0063

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