Primary 2 Numbers to 1000
Build a three-digit number, look for pairs, and follow number changes. Let the pictures explain each idea before reading the rule.
Three-digit place value
One hundred is ten tens. Choose a number and see its digits in the place-value chart and its hundreds, tens and ones as blocks. A zero means there are no blocks in that place.
| Hundreds | Tens | Ones | |
|---|---|---|---|
| Digit | 4 | 7 | 2 |
| Value | 400 | 70 | 2 |
At 1000: Ten hundreds can be exchanged for one thousand. Write 1000 as 1 thousand, 0 hundreds, 0 tens and 0 ones.
Ask: “What is each digit worth? What does the zero in 305 tell us?”
Reading and writing numbers
Read the hundreds first, then the tens and ones. When writing a numeral from words, put each digit in its place. Use 0 if a place is empty.
Read a numeral in words
472
four hundred and seventy-two
Write words as a numeral
four hundred and seventy-two
Write 472.
4 hundreds, 7 tens and 2 ones make 472.
At 1000: The numeral 1000 is written one thousand in words.
- Writing 35 for “three hundred and five”. The tens place is empty, so write 305.
- Writing 427 for “four hundred and seventy-two”. The 7 belongs in the tens place and the 2 in the ones place: 472.
- Spelling forty as “fourty” or ninety as “ninty”. Check the tens word before adding a hyphen and the ones word.
- Writing 100 for “one thousand”. Ten hundreds make 1000.
Ask: “Which word tells you the hundreds? Do you need a zero to hold an empty place?”
Comparing and ordering numbers
To decide which number is more than (>) or less than (<) another, compare the hundreds first. If they are the same, compare the tens. If the tens are the same too, compare the ones.
Compare two numbers
| Number | Hundreds | Tens | Ones |
|---|---|---|---|
| 472 | 4 | 7 | 2 |
| 563 | 5 | 6 | 3 |
Compare hundreds first: 4 hundreds is less than 5 hundreds.
472 is less than 563. Write 472 < 563.
Order several numbers
Use the same place-by-place check to put numbers in order. Start with the hundreds, then use tens or ones to break a tie.
Numbers to order: 503, 350, 309, 305
Common mistake: Choosing 438 as more than 472 because 8 ones is more than 2 ones. The hundreds are equal, so compare tens next: 7 tens is more than 3 tens. Therefore 472 > 438.
Ask: “Are the hundreds the same? If so, which place do we compare next?”
Odd and even numbers
Make pairs to decide if a number is odd or even. If every one has a partner, the number is even. If one is left without a partner, it is odd.
Even ending digits
0 · 2 · 4 · 6 · 8
All the ones can be paired. Zero is even too: none are left over.
Odd ending digits
1 · 3 · 5 · 7 · 9
After pairing the ones, one is left without a partner.
Try each ending digit
Choose a digit from 0 to 9. Pair its ones and look for one left over.
Check a three-digit number
Hundreds and tens already make complete pairs. Look only at the last digit, the ones digit.
Common mistake: Calling 305 even because it contains a 0. Check the last digit: 305 ends in 5, so it is odd.
Ask: “Can every one find a partner? Which digit helped you decide?”
Number patterns
Look at the change between neighbouring numbers. Then use the same change again. Watch which place changes when you cross a ten or a hundred.
Ask: “What stayed the same? Which place changed? Does your rule work for every jump?”