Videos and solutions to help Kindergarten and Grade 1 kids learn to add and subtract within 20, demonstrating fluency for addition and subtraction within 10 by using decomposing a number leading to a ten (e.g., 13 – 4 = 13 – 3 – 1 = 10 – 1 = 9).

**Related Pages**

Make Ten Addition

Lesson Plans And Worksheets For Grade 1

More Lessons For Grade 1

Common Core For Grade 1

**Common Core: 1.OA.6**

- I can add and subtract within 10 easily.
- I can add and subtract by making 10. (e.g. 7 + 3 = 10, 10 - 6 = 4)

The following diagrams show the Make Ten Subtraction Strategy. Scroll down the page for more examples and solutions.

**Mental Math Strategies: Break Down To 10**

How to use mental strategies to subtract within 20 using the “break down to 10” strategy?

This is one of the strategies suggested in the Common Core State Standards for Mathematics, 1.OA.6 and 2.OA.2.

With practice, this strategy can help students gain fluency when subtracting within 20. Eventually students will memorize these facts, which is expected by the end of grade 2.

**Example:**

14 - 9 = 14 - 4 - 5 = 10 - 5 = 5

15 - 7 = 15 - 5 - 2 = 10 - 2 = 8

17 - 8 = 17 - 7 - 1 = 10 - 1 = 9

**Make 10 Subtraction Strategy**

**Example:**

11 - 6 = 11 - 1 - 5 = 10 - 5 = 5

13 - 9 = 13 - 3 - 6 = 10 - 6 = 4

17 - 8 = 17 - 7 - 1 = 10 - 1 = 9

14 - 7 = 14 - 4 - 3 = 10 - 3 = 7

**Subtraction With The Make A Ten Strategy**

**Example:**

12 - 9 = 12 - 2 - 7 = 10 - 7 = 3

**Using Ten: a Mental Math Subtraction Strategy**

Using Ten is a mental math strategy that involves changing a number to ten and then adjusting the answer. Because “10” is generally an easier number to work with, this simplifies the equation making it easier to solve.

**Example:**

13 - 8 = 10 - 8 + 3 = 5

Try the free Mathway calculator and
problem solver below to practice various math topics. Try the given examples, or type in your own
problem and check your answer with the step-by-step explanations.

We welcome your feedback, comments and questions about this site or page. Please submit your feedback or enquiries via our Feedback page.