Our number system is called Base 10. This means that all of our numbers go through the same rotating 10 digits. Every number uses one or more digits from 0 through 9. Our numbers also go through a pattern, so that when one place value reaches 9, it then starts over again at 0 and adds one to the place value to the left. As adults, counting is second nature to us and we probably don’t notice these patterns unless we sit down and look at them, but for kids number patterns can be a great tool. We are going to start by looking at one more and ten more. You can expand on this idea for older students by thinking of 100 more or even 1000 more. In fact, once a child gets the hang of it, there are endless possibilities!
One more is a pretty easy concept. For students that are already counting, one more is simply the next number in order. The trickiest part comes when we change to the next place value. For example, from 29 to 30, or from 89 to 90. A great tool for this is practicing how to count by 10’s. A 100 chart can be a handy visual, like the one below. Once a student can count by tens, if they get stuck when changing place values just recall their counting by 10’s knowledge. For example, “what comes after 20 when counting by 10’s? – 30. So what comes after 29? 30.” They can start to see how the tens place can help.
This leads us right into the skill of Ten More. Again, the 100 chart is a great visual to see. Let’s go back to counting by 10’s. Your student probably has noticed that all the numbers they say when counting by 10 are in the far left column. That means that every number below another number is the 100 chart is 10 more. Because of this, we can count by 10 from any number not just starting at 10. Try these 100 charts with your child and see if they can count by 10’s from the starting numbers. Once they get the hang of it, try it without looking.
Using Base 10 Blocks
Our ultimate goal is for every student to be able to answer the question “what is one more” or “what is ten more” to any number. While the 100 chart is a great visual, we hope that students can learn to mentally find these numbers. If your child is struggling to make that jump, base 10 blocks could be a good stepping stone to independence. They should be familiar with these, and know that a ten looks like this:
and a one looks like this:
Now see if they can answer the questions, “what is one more and what is ten more?” After they have made their guess, add one more to see if they are right, then add ten more (be sure to take away the “one more” before you test the “ten more” so you don’t end up with 11 more!).
One More and Ten More in Addition
The skill of finding one more and ten more can help your child as they start addition. Now your child can answer questions like 32 + 10 without having to sit down and compute the answer. Since they know that 10 more means adding a ten, they can easily manipulate the number 32 to see that 10 more would make 42.
Common Core math is all about making math make sense. It is also about helping students find short cuts to solve problems, rather than only knowing one way to solve something. Remember, the steps to teaching these skills may seem long and unnecessary, but when your child has mastered these steps, math will be easier and less complicated in the end.
Common Core Math Standards
Add within 100, including adding a two-digit number and a one-digit number, and adding a two-digit number and a multiple of 10, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used. Understand that in adding two-digit numbers, one adds tens and tens, ones and ones; and sometimes it is necessary to compose a ten.
Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
Mentally add 10 or 100 to a given number 100-900, and mentally subtract 10 or 100 from a given number 100-900.