Number Talks are a daily routine used to teach mental math strategies.
Make a Ten: To add 2 + 6 + 8 + 3 + 4, add the 8 and 2 to make a ten, then the 6 and 4 to make another ten. Add those to get 20, and finally add the 3 to get 23.
Make a Landmark or Friendly Number: When you have addends that are one or two away from a multiple of ten or a landmark number, this is the strategy to use. For instance, to add 99 + 38, simply take one away from the 38 to make it 37, and add that to the 99 to make it 100. Then add 100 + 37 to get 137.
Use Doubles or Near Doubles: When one of the addends is one or two away from their double, use this strategy. For instance, if you know 5 + 5 = 10, then you can easily find 5 + 6 or 5 + 7 by thinking of the double fact and then adding one or two more. This works for larger numbers as well. If I know 25 + 25 = 50, then I know 25 + 27 = 52 by thinking first of the doubles fact for 25 + 25, and then adding 2 more.
Breaking Each Number into Its Place Value: When adding 2 or 3 digit numbers mentally, it is easier to break the numbers into their place value and add them. Sometimes, you can break the numbers apart into their place value, and then make a landmark/friendly number. For instance, when adding 38 + 56, students will often break the numbers apart into 30 + 8 + 50 + 6. Next, they will subtract 2 from the six, and add it to the eight to make another ten. Thus creating 30 + 10 + 50 + 4, with the resulting answer being 94.
Adding in Chunks: This week's number talks consist of adding multiples of ten while keeping one number whole and then breaking apart the ones into friendly combinations. For example, 28 + 24 could be chunked as 28 + 20 = 48; the 48 + 4 could be added by breaking the 4 apart into 2 + 2. The problem could then be solved as (48 + 2) + 2 =50 + 2 = 52.
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