One more and one less help young learners understand how numbers sit next to each other. When we count forward by 1, we find one more. When we count backward by 1, we find one less.
This idea matters because it builds the foundation for addition, subtraction, and number sense.
A number line shows numbers in order from left to right, so it is a helpful tool for seeing number neighbors. The number just after a number is one more, and the number just before it is one less. Cubes make the idea easier to see because adding one cube shows one more, and taking away one cube shows one less.
Learners can connect counting, moving on a number line, and changing a group of objects by 1.
Key Facts
- One more means add 1.
- One less means subtract 1.
- n + 1 = one more than n.
- n - 1 = one less than n.
- On a number line, one more is one step to the right.
- On a number line, one less is one step to the left.
Vocabulary
- One more
- One more is the number you get when you add 1 to a number.
- One less
- One less is the number you get when you take away 1 from a number.
- Number line
- A number line is a line that shows numbers in order.
- Next number
- The next number is the number that comes right after a number when counting forward.
- Number before
- The number before is the number that comes right before a number when counting backward.
Common Mistakes to Avoid
- Saying one more means go backward is wrong because one more means add 1 and move to the next number.
- Saying one less means go forward is wrong because one less means take away 1 and move to the number before.
- Skipping a number on the number line is wrong because one more or one less is only one step away.
- Counting the starting number as the extra one is wrong because one more means adding one new object or moving one new step.
Practice Questions
- 1 Start at 6 on a number line. What number is one more than 6?
- 2 You have 9 cubes. If you take away 1 cube, how many cubes do you have now?
- 3 Mia says one less than 5 is 6 because 6 is close to 5. Explain why her answer is not correct and name the correct number.