"How many more" word problems and the concept of difference (2nd grade math)
The difference between two numbers is their distance; how far apart they are from each other on a number line. We look at this concept, and how it ties in with subtraction and addition. This lesson is meant for 2nd or 3rd grade.
(Note: the video uses the terminology "difference of" instead of "difference between". It means the same thing.)
We can always SUBTRACT the two numbers to find their difference. For example, to find the difference of 100 and 3, subtract 100 − 3. The difference is 97.
We can also use this idea to solve subtractions, especially those where the two numbers are fairly close to each other. What is 98 − 95? Think how far apart 98 and 95 are from each other. Just three steps. So, 98 − 95 = 3.
Lastly, the difference between two numbers can also be solved by thinking of "how many more" type of an addition. For example, to find the difference between 7 and 12, think: 7 + ____ = 12, or 7 and how many more makes 12? This ties in with the number line: if you are at 7, how many steps do you need to take to get to 12?
If you cannot see the video above, click here for an alternative video player.
In the 2nd part of the lesson, we have just a silly word problem that my mascot Mathy made up: Who did more jumping jacks, Mathy or Giganto? (They're both mammoths.) And how many more? Just an example word problem for 2nd grade math. :)
See also
Number rainbow & fact families with 11
Number rainbow & fact families with 12
Math Mammoth Grade 2 curriculum