What is Doubles Minus 1?
Doubles minus 1 is a strategy used to add two consecutive numbers that is, when they are next to each other. We simply add the bigger number twice or double it and then, subtract 1 from it, to get the final result.
Here, for example, consecutive number 7 and 8 have been added using the doubles minus one strategy.
Here are more examples of the double minus 1 strategy.
| Fun Facts – Doubles minus 1 and doubles plus 1 are also called near doubles strategies. |
Let’s sing!
Let’s add consecutive soap bubbles,
Adding five and six; there’s no trouble!
Just make the bigger number double,
Subtract 1 from the double of bubbles.
Let’s do it!
Have fun with your child by asking them to find the doubles of numbers you say and then use double minus 1 and doubles plus 1 strategies to find the sum of consecutive numbers between 1 and 20.
Related Math Vocabulary