Numbers up to 1000
Primary 3 · Mathematics
Numbers up to 1000
Lesson 3 of 3
12 min
On Saturday, Uwase sold avocados and took home 348 Frw. Her brother Mugisha sold tomatoes and took home 429 Frw.
Both of them say, "I sold more!" Who is right?
You cannot settle this by shouting. You settle it by comparing the numbers — and there is a rule that always works.
| Sign | It means | Example |
|---|---|---|
| > | is greater than | 500 > 200 |
| < | is less than | 200 < 500 |
| = | is equal to | 305 = 305 |
Look at the shape of > and <. One end is wide open, like a hungry mouth. The other end is a sharp little point.
The open mouth always turns towards the bigger number. The sharp point always turns towards the smaller one.
To compare two three-digit numbers, do not look at all the digits at once. Go one seat at a time, starting from the left.
Hundreds first. If they are the same, look at the tens. If those are the same too, look at the ones.
Stop as soon as you find a difference. You have your answer.
This is Uwase and Mugisha's problem.
Hundreds: 348 has 3 hundreds. 429 has 4 hundreds. They are different, so stop right here — you do not need the other digits at all.
4 hundreds beats 3 hundreds. So 429 is the bigger number.
429 > 348, which is the same as saying 348 < 429.
Mugisha sold more. Uwase must clap for her brother.
Hundreds: 5 and 5. The same! Keep going.
Tens: 562 has 6 tens. 548 has 4 tens. Different — stop.
6 tens beats 4 tens, so 562 > 548.
Hundreds: 2 and 2. The same.
Tens: 7 and 7. The same again.
Ones: 1 and 4. Different — stop. 4 is bigger.
So 271 < 274. Even a single one can decide a race.
Some children look at 89 and say, "8 and 9 are big digits, and 300 only has a 3 — so 89 must win."
No. Count the digits first. 89 has only two digits, so it has no hundreds at all. 300 has three digits. A number with fewer digits is always smaller.
89 < 300.
Ordering is just comparing, again and again. Try this set:
418, 184, 481, 148 — arrange them from smallest to largest.
Step 1. Sort them into hundreds groups. Two of them start with 1 (184 and 148). Two of them start with 4 (418 and 481). Everything starting with 1 is smaller than everything starting with 4.
Step 2. Sort inside each group using the tens.
184 and 148: the tens are 8 and 4. So 148 comes before 184.
418 and 481: the tens are 1 and 8. So 418 comes before 481.
Step 3. Write the whole line out.
148, 184, 418, 481
Smallest to largest is called ascending order — think of climbing a hill. To go from largest to smallest, just read your answer backwards: 481, 418, 184, 148.
Tip
The hungry mouth. The wide open end of > or < always eats the bigger number. The sharp point pokes the smaller one.
703 > 307 — the mouth opened towards 703, so 703 is greater.
And always compare from the left. Hundreds, then tens, then ones. Stop at the first difference you find.
Work each one out, then tap Show answer to check.
Put in the right sign: 637 ___ 673
Answer: <. The hundreds are both 6, so look at the tens: 3 and 7. 7 is bigger, so 637 < 673.
Put in the right sign: 900 ___ 899
Answer: >. The hundreds are 9 and 8. 9 beats 8, so 900 > 899. (899 has more tens and more ones, but hundreds are checked first — they win.)
Put in the right sign: 512 ___ 512
Answer: =. Every seat matches, so the numbers are equal.
Arrange from smallest to largest: 706, 670, 760, 607
Answer: 607, 670, 706, 760. First split by hundreds: 607 and 670 have 6 hundreds; 706 and 760 have 7 hundreds. Then use the tens inside each pair.
Using the digits 3, 9 and 5 once each, make the largest number you can, and the smallest.
Answer: Largest is 953 — put the biggest digit in the hundreds seat, because that seat is worth the most. Smallest is 359.
What you learned today
Quick check
458 ___ 485. Which sign goes in the gap?
