Subtract more than 4-digit numbers | Year 6 Mathematics PDF Download

Subtracting Numbers Using the Column Method

• Start by subtracting numbers using the column method, which is a systematic way of performing subtraction.
• Let's delve into an example to understand how to subtract 4-digit numbers using this method.

Examples

Example 1: What is 12,328 - 3,167?
Sol:

• Start from the ones column: 8 - 7 = 1.
  
• In the tens column, you can’t take 60 away from 20, so you have to exchange a hundred from three hundred. 120 - 60 = 60.
  
• In the hundreds column: 200 - 100 = 100.
  
• In the thousands column, you need to exchange from the ten thousands. 12,000 - 3,000 = 9,000.
  
• The final result of 12,328 - 3,167 is 9,161.

Example 2: Harry has worked out the following subtraction: 34,256 - 12,382 = 22,974. Is he correct?
Sol: The best thing to do is work out the answer for ourselves since Harry hasn’t shown whether he has exchanged any numbers.

• Start with the ones column: 6 - 2 = 4.
  
• In the tens column, you can’t subtract 80 from 50, so you need to exchange a hundred. This makes 150 - 80 = 70. Remember to reduce the number of hundreds after you have exchanged!
  
• In the hundreds column, you can't subtract 300 from 100, so you exchange a thousand to make it 1,100 - 300 = 800.
  
• In the thousands column: 3,000 - 2,000 = 1,000.
  
• In the ten thousands column: 30,000 - 10,000 = 20,000.
  
• The final result of 34,256 - 12,382 is 21,874.

Harry's answer of 22,974 is incorrect because he forgot to reduce the number of hundreds after exchanging a ten. The correct answer is 21,874.

Checklist

• Use the column method to facilitate subtraction of large numbers.
• Separate the numbers according to their place values: ones, tens, hundreds, and thousands.
• Begin the subtraction from the rightmost column, starting with the ones column.
• Before starting, estimate the answer to gauge reasonableness.
• Subtraction is the inverse operation of addition, so it can be verified by addition. For instance, verify that 11,282 - 4,237 = 7,045 by calculating 7,045 + 4,237 = 11,282.
• Watch for these keywords in problems: take away, difference, less than, minus, decrease, fewer than, reduce. They all signify subtraction.