Subtraction facts – numbers up to 18

key notes :

Introduction to Subtraction

  • Subtraction is the process of taking away one number from another.
  • It is the opposite of addition.

Subtraction Symbols

  • The subtraction sign is (-), and the result is called the “difference.”

Numbers within 18

  • Subtraction facts focus on numbers up to 18.
  • Examples: 18 – 2 = 16, 15 – 5 = 10.

Zero Property of Subtraction

  • Any number minus 0 remains the same.
  • Example: 7 – 0 = 7.

Subtraction from Itself

  • Any number minus itself equals 0.
  • Example: 8 – 8 = 0.

Counting Backwards

  • Subtraction can be visualized as counting backwards on a number line.
  • Example: Start at 12 and count back 3 steps to get 9.

Relation Between Addition and Subtraction

  • Subtraction facts are linked to addition facts.
  • Example: If 5 + 3 = 8, then 8 – 3 = 5.

Learn with an example

♦️Subtract. 14–7=

  • You can count back to find 14–7. Start at 14 and count back 7 times.
  • You end at 7.
  • 14–7=7

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  • You can also use 10 to find 14–7.
  • Start at 14. Subtract 4 to get to 10. Then subtract 3 more. That way, you subtract 7 in all.
  • You end at 7.
  • 14–7=7

♦️Subtract. 9–3=

  • You can count back to find 9–3. Start at 9 and count back 3 times.
  • You end at 6.
  • 9–3=6

♦️Subtract. 8–7=

  • You can count on to find 8–7. Start at 7. Count on until you reach 8.
  • You counted on 1 time.
  • 8–7=1

Let’s practice!