Topic 4 of 8
Step 3: Adding and subtracting to 20
Tens and ones
Step 3 · Adding and subtracting to 20 topics
A two-digit number is made of tens and ones. Bundle ten ones into a ten, and read what each digit means.
Bundling ten ones into a ten
Counting lots of things is easier in tens. Bundle 10 ones and you have one ten. 10 is one ten and no ones.
The tens numbers are bundles with no loose ones: 20 is 2 tens, 50 is 5 tens, 90 is 9 tens.
What each digit means
In a two-digit number, the left digit counts the tens and the right digit counts the ones. In 47, the 4 means 4 tens, which is 40, and the 7 means 7 ones.
| Number | Tens | Ones |
|---|---|---|
| 47 | 4 | 7 |
| 30 | 3 | 0 |
| 82 | 8 | 2 |
| 15 | 1 | 5 |
A 0 in the ones place means no extra ones: 60 is 6 tens and 0 ones.
Writing a number as tens and ones
Count the tens, then the ones, and write the digits in that order. 3 tens and 6 ones is 36.
Example: Too many ones
What number is 3 tens and 14 ones?
- 14 ones is enough to make another ten: 1 ten and 4 ones.
- So there are 4 tens and 4 ones in all.
Answer44
Try it yourself
Work each one on paper first, then open the answer to check.
How many tens are in 70?
Show answer
7.
What number is 6 tens and 3 ones?
Show answer
63.
In 58, what is the 5 worth?
Show answer
5 tens, which is 50.
How many ones are in 91, beyond the tens?
Show answer
1.
What number is 2 tens and 12 ones?
Show answer
32, because 12 ones is 1 ten and 2 ones.