Three- and four-digit numbers · Usually met around P2
Comparing and ordering numbers
Count the digits, then compare from the biggest place.
How to do it
Method
Count the digits, then compare from the biggest place
3405 and 3450: tens 0 < 5 → 3405 < 3450
Another way
Number line
3450 is right of 3405, so it is bigger
In full
Count the digits first: a four-digit number is always bigger than a three-digit one. With the same number of digits, compare from the biggest place: thousands first, and the bigger thousands digit wins; if those match, compare the hundreds, and so on. 3405 and 3450: both have 3 thousands and 4 hundreds, and the tens are 0 < 5, so 3405 < 3450. “>” means greater than and “<” less than: the open side faces the bigger number. To put numbers in order, pick out the smallest (or biggest) one at a time. Or place them on a number line: the further right, the bigger.
Worked examples
Have a go first, then open each one for the answer and the working.
Example 1
Which of these numbers is the biggest?
- A. 761
- B. 716
- C. 671
- D. 167
Choose the right answer
Show the answer and working
Answer: A. 761
All four use the same digits. Compare the hundreds: the biggest hundreds digit gives the biggest number; if two match, compare the tens.
Example 2
7□0 > 780. What is the smallest digit that can go in □?
Show the answer and working
Answer: 9
The hundreds and ones match, so the tens digit must be bigger than 8: the smallest is 9.
Example 3
Make four-digit numbers from the cards 7, 5, 6 and 4, each used once. The biggest is □ and the smallest is □.
Fill in each box
Show the answer and working
Answer: 7654，4567
Biggest: biggest digit first, 7 in the thousands. Smallest: smallest first, 4 in the thousands.
Practise it in the game →Three- and four-digit numbers · Free to start, unlimited questions, no download