You know that 14 is ten and four more, and you can count to 120. Bigger numbers work the same way, with more tens.
Key idea
In a two-digit number, the left digit tells how many tens. The right digit tells how many ones. 47 is 4 tens and 7 ones.
Why it works
We bundle ones into groups of ten so big numbers are quick to count and write. Each bundle is worth 10.
Worked example: Tens and ones
What number is 6 tens and 3 ones?
- 6 tens is 60.
- 60 and 3 more is 63.
Answer: 63
Common mistake
Thinking the 4 in 47 means just 4. It means 4 tens, which is 40! Count the ten-sticks by tens to check.
For grown-ups: Bundle straws, craft sticks or pasta into tens with rubber bands. Build numbers and say them: “3 tens and 5 ones is 35.”