Numbers to 100
Counting up to 100 objects
When you know the order of the numbers to 100, you can estimate how many objects there are and count to check. Counting in groups helps you count quickly.
Estimate then count
First make an estimate ā a sensible guess of how many objects there are. Then count to check. A good estimate is close to the real number.
Make groups of ten
Draw a ring around groups of 10 objects. Count in tens, then count the ones that are left. For 45 objects you make 4 rings of ten (40) and have 5 ones left, so 40 + 5 = 45.
Counting in twos, fives and tens
Counting in bigger steps is faster than counting in ones. ā¢ Twos: 2, 4, 6, 8, 10 (even numbers). ā¢ Fives: 5, 10, 15, 20. ā¢ Tens: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100.
Odd and even
When you count in twos from 0 you only say even numbers. You skip the odd numbers like 15 and 37.
Worked examples
Grouping into tens and ones
- You have 45 objects.
- Make rings of 10: you get 4 rings, so 4 tens is 40.
- Count the ones left over: 5.
Answer: 45 is 4 tens and 5 ones.
Counting in tens
- You have 6 groups of 10.
- Count in tens: 10, 20, 30, 40, 50, 60.
Answer: 6 groups of 10 make 60.
Counting in twos
- Start at 2.
- Add 2 each time: 2, 4, 6, 8.
Answer: The next number after 6 is 8.
Estimate then check
- Look at a pile and make a guess (estimate).
- Then group into tens and count to check.
Answer: A good estimate is close to the number you count.
Where you see this in real life
- Counting how many stickers are in your collection.
- Counting a big box of crayons by making groups of ten.
- Guessing how many sweets are in a jar, then counting to check.
Key words
- Estimate
- A sensible guess of how many before you count.
- Collection
- A group of objects you want to count.
- Even number
- A number you say when counting in twos from 0, like 2, 4, 6.
- Tens
- Groups of ten. Counting in tens helps you count quickly.