Add using doubles plus one

Key notes:-

Doubles Facts: Doubles are when you add the same number to itself. For example:

  • 2 + 2 = 4
  • 3 + 3 = 6

Doubles Plus One: When a number is one more than the other, you use the nearest doubles fact and add one. For example:

  • 2 + 3 = (2 + 2) + 1 = 4 + 1 = 5
  • 4 + 5 = (4 + 4) + 1 = 8 + 1 = 9

Steps:

  1. Recognize a Near Double: Identify that one of the numbers is 1 more than the other.
  2. Use the Double Fact: Add the double fact for the smaller number.
  3. Add One: After getting the result of the double, add 1 more.

Example Problems:

  • 7 + 8: (7 + 7) + 1 = 14 + 1 = 15
  • 5 + 6: (5 + 5) + 1 = 10 + 1 = 11

Learn with an example

🖊️Add the near doubles.
Hint: use the doubles fact 2 + 2 = 4.
2 + 3 =

  • To add 2 + 3, you can use the strategy of doubles plus one. This is because 2 and 3 are near doubles.
  • Break 3 into 2 + 1 to make double 2s.
  • 2 + 3 = 2 + 2 + 1
  • Add the double 2s. Use the doubles fact 2 + 2 = 4.
  • 2 + 2 + 1 = 4 +1
  • Add 1.
  • 4 + 1 = 5
  • So, 2 + 3 = 5.

🖊️Add the near doubles.
Hint: use the doubles fact 3 + 3 = 6.
3 + 4 =

  • To add 3 + 4, you can use the strategy of doubles plus one. This is because 3 and 4 are near doubles.
  • Break 4 into 3 + 1 to make double 3s.
  • 3 + 4 = 3 + 3 + 1
  • Add the double 3s. Use the doubles fact 3 + 3 = 6.
  • 3 + 3 + 1 = 6 + 1
  • Add 1.
  • 6 + 1 = 7
  • So, 3 + 4 = 7.
  • So, 2 + 3 = 5.

🖊️Add the near doubles.
Hint: use the doubles fact 5 + 5 = 10.
5 + 6 =

  • To add 5 + 6, you can use the strategy of doubles plus one. This is because 5 and 6 are near doubles.
  • Break 6 into 5 + 1 to make double 5s.
  • 5 + 6 = 5 + 5 +1
  • Add the double 5s. Use the doubles fact 5 + 5 = 10.
  • 5 + 5 + 1 = 10 + 1
  • Add 1.
  • 10 + 1 = 11
  • So, 5 + 6 = 11.

let’s practice!