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Step-by-step practice: Maths · Level 4Chapter 3 · Column addition and subtraction
Step-by-step Maths Level 4 · Column addition and subtraction · Lesson 3.4

Step-by-step Maths Level 4: Subtraction with a zero in the middle

Part of the Step-by-step Maths Level 4 column addition and subtraction chapter. Chapter overview · whole chapter on one page

3.4

Subtraction with a zero in the middle

Level 4
Subtract across a zero in the middle of the top number, exchanging from the nearest non-zero column

A zero cannot give a ten. In 5004 - 2378 there are no tens and no hundreds to exchange from.

Go left to the first column that is not zero. Exchange 1 from there, then make each zero 9 as you go along.

Key ideas

  • A zero cannot be exchanged from.
  • Exchange from the first column on the left that is not zero.
  • Each zero that you pass becomes 9.
Worked example 3.4.1
Work out 5004 - 2378.

Method. Subtract column by column from the ones. When the top digit is too small, exchange from the column on the left.

  1. Exchange in the thousands column. The hundreds are 0, so exchange from further left: exchange 1 thousand for 10 hundreds.
    thousands: 5 to 4; hundreds: 0 to 10
  2. Exchange in the hundreds column. The tens are 0, so exchange from further left: exchange 1 hundred for 10 tens.
    hundreds: 10 to 9; tens: 0 to 10
  3. Exchange in the tens column. The ones digit is too small, so exchange 1 ten for 10 ones.
    tens: 10 to 9; ones: 4 to 14
  4. Subtract the ones column. Take the bottom digit from the top digit.
    14 - 8 = 6
  5. Subtract the tens column. Take the bottom digit from the top digit.
    9 - 7 = 2
  6. Subtract the hundreds column. Take the bottom digit from the top digit.
    9 - 3 = 6
  7. Subtract the thousands column. Take the bottom digit from the top digit.
    4 - 2 = 2
  8. Write the answer. Read the digits from the top: thousands, hundreds, tens and ones.
    2626

Check. Check: 2626 + 2378 = 5004.

Watch out. A zero cannot give a ten. Go left to the first column that is not zero, and exchange from there.

Worked example 3.4.2
Work out 3001 - 1245.

Method. Subtract column by column from the ones. When the top digit is too small, exchange from the column on the left.

  1. Exchange in the thousands column. The hundreds are 0, so exchange from further left: exchange 1 thousand for 10 hundreds.
    thousands: 3 to 2; hundreds: 0 to 10
  2. Exchange in the hundreds column. The tens are 0, so exchange from further left: exchange 1 hundred for 10 tens.
    hundreds: 10 to 9; tens: 0 to 10
  3. Exchange in the tens column. The ones digit is too small, so exchange 1 ten for 10 ones.
    tens: 10 to 9; ones: 1 to 11
  4. Subtract the ones column. Take the bottom digit from the top digit.
    11 - 5 = 6
  5. Subtract the tens column. Take the bottom digit from the top digit.
    9 - 4 = 5
  6. Subtract the hundreds column. Take the bottom digit from the top digit.
    9 - 2 = 7
  7. Subtract the thousands column. Take the bottom digit from the top digit.
    2 - 1 = 1
  8. Write the answer. Read the digits from the top: thousands, hundreds, tens and ones.
    1756

Check. Check: 1756 + 1245 = 3001.

Watch out. A zero cannot give a ten. Go left to the first column that is not zero, and exchange from there.

Worked example 3.4.3
Work out 4500 - 1268.

Method. Subtract column by column from the ones. When the top digit is too small, exchange from the column on the left.

  1. Exchange in the hundreds column. The tens are 0, so exchange from further left: exchange 1 hundred for 10 tens.
    hundreds: 5 to 4; tens: 0 to 10
  2. Exchange in the tens column. The ones digit is too small, so exchange 1 ten for 10 ones.
    tens: 10 to 9; ones: 0 to 10
  3. Subtract the ones column. Take the bottom digit from the top digit.
    10 - 8 = 2
  4. Subtract the tens column. Take the bottom digit from the top digit.
    9 - 6 = 3
  5. Subtract the hundreds column. Take the bottom digit from the top digit.
    4 - 2 = 2
  6. Subtract the thousands column. Take the bottom digit from the top digit.
    4 - 1 = 3
  7. Write the answer. Read the digits from the top: thousands, hundreds, tens and ones.
    3232

Check. Check: 3232 + 1268 = 4500.

Watch out. A zero cannot give a ten. Go left to the first column that is not zero, and exchange from there.

Watch out

Watch out. 5004 - 2378 is 2626, not 2636. Each zero becomes 9 after the exchange, and the last column gets 10 more.

Exam tip

Grown-up tip. Ask the child to point to the first non-zero digit on the left before exchanging.

Exercise 3D  Practice: subtraction across zeros

Non-calculator
1
FWork out 4078 - 3893.
2
FWork out 2070 - 1782.
3
FWork out 5048 - 4288.
4
FWork out 9072 - 2185.
5
FWork out 9072 - 1191.
6
FWork out 5050 - 4757.
7
FWork out 8078 - 1599.
8
FWork out 4002 - 1488.
9
FWork out 6005 - 1576.
10
FWork out 2002 - 1590.
11
FWork out 2012 - 1408.
12
FWork out 3041 - 2160.
13
FWork out 8038 - 6543.
14
FWork out 2066 - 1683.
15
FWork out 8022 - 3085.
16
FWork out 6041 - 3803.

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