A hundred chart is a helpful tool for seeing how numbers are organized from 1 to 100. Early learners can use it to find numbers that are ten more or ten less without counting one by one. When you move down one row on the chart, the number gets 10 bigger.
When you move up one row, the number gets 10 smaller.
This works because each row of a hundred chart has 10 numbers. For example, starting at 34 and moving down one row lands on 44, so 44 is ten more than 34. Moving up one row from 34 lands on 24, so 24 is ten less than 34.
Stacks of ten cubes and jumps by tens show the same idea in a hands-on way.
Key Facts
- Ten more means add 10: n + 10.
- Ten less means subtract 10: n - 10.
- On a hundred chart, moving down one row means ten more.
- On a hundred chart, moving up one row means ten less.
- Example: 34 + 10 = 44 and 34 - 10 = 24.
- The ones digit usually stays the same when adding or subtracting 10.
Vocabulary
- Hundred chart
- A hundred chart is a grid that shows the numbers 1 to 100 in order.
- Ten more
- Ten more is the number you get when you add 10 to a number.
- Ten less
- Ten less is the number you get when you subtract 10 from a number.
- Row
- A row is a line of numbers that goes across the chart from left to right.
- Tens digit
- The tens digit shows how many groups of ten are in a number.
Common Mistakes to Avoid
- Moving right to find ten more is wrong because moving right only adds 1 on a hundred chart. To find ten more, move down one row.
- Moving left to find ten less is wrong because moving left only subtracts 1. To find ten less, move up one row.
- Changing the ones digit when adding 10 is often wrong because the ones digit usually stays the same. For example, 34 + 10 = 44, not 35.
- Counting every number one by one can lead to mistakes and takes longer. Use the chart pattern or add and subtract 10 instead.
Practice Questions
- 1 Start at 27 on a hundred chart. What number is ten more?
- 2 Start at 58 on a hundred chart. What number is ten less?
- 3 Mia is on 46. She moves down one row, then up one row. Explain where she ends and why.