Place Values of Digits up to 99

Every number is built from digits, and each digit has a job depending on where it sits. This is called place value: the idea that the position of a digit tells you how much it is really worth. For numbers up to 99, there are only two positions to worry about, the tens place and the ones place, which makes this a great starting point before moving on to bigger numbers.

For example, in the number 47, the digit 4 is not just "4." Because it sits in the tens place, it stands for 4 tens, or 40. The digit 7 sits in the ones place, so it stands for 7 ones, or just 7. Put together, 40 and 7 make 47.

Every two-digit number can be split into a tens digit and a ones digit. The digit on the left is the tens digit, and the digit on the right is the ones digit. Understanding this split is the foundation for reading, writing, and comparing numbers, and it connects closely to identifying tens and ones in a number.

To find the place value of a digit, first identify its position, then multiply it by what that position is worth. The ones place is worth 1, and the tens place is worth 10.

Take the number 58. The digit 5 is in the tens place, so its place value is 5 times 10, which is 50. The digit 8 is in the ones place, so its place value is 8 times 1, which is 8. Adding these together, \(50 + 8 = 58\), matches the original number. Writing a number this way, as a sum of its place values, is the same idea covered in more detail in numeral expanding up to 99.

Find the place value of each digit in 93.

The digit 9 is in the tens place, so it represents 9 tens, or 90. The digit 3 is in the ones place, so it represents 3 ones, or 3. Checking the sum, \(90 + 3 = 93\), confirms the digits are placed correctly.

Now try 20. Here the digit 2 is in the tens place, giving 2 tens, or 20, and the digit 0 is in the ones place, giving 0 ones. Since \(20 + 0 = 20\), the zero in the ones place simply means there are no extra ones to add. Practicing this kind of breakdown for many numbers is exactly the skill built in counting the value of a digit up to 99.

Place value explains why 47 and 74 are different numbers even though they use the same two digits. In 47, the 4 is worth 40 and the 7 is worth 7. In 74, the 7 is worth 70 and the 4 is worth 4. Swapping the digits changes their positions, which changes the whole value of the number. This idea becomes especially useful once numbers need to be compared, since knowing which digit carries more weight helps decide which number is larger.

Getting comfortable with tens and ones for numbers up to 99 sets up every later skill, from adding two-digit numbers to understanding hundreds and thousands, since the same tens-and-ones thinking simply repeats with new positions added on.

Related lessons

• Math 1