3rd grade math question, anyone know a answer, on son's homework!?

Question

Writing in Math: How does knowing 30+7=37 help you find 37+23?

I think this is a very confusing question for a third grader!

Answer 1

30+7=37

23+30+7

23+7=30

30+30=60

It teaches them how to break up large numbers and do mental math easier. Hope this helps!

Answer 2

I think we need to bring ourselves down to a 3rd grade level.
Assume limited mathematical knowledge: addition, but not subtraction, addition of single digit (at least mentally) but not 2 or more digits numbers.

So, 37 + 23 is a difficult evaluation.
With the knowledge of 37 = 30 + 7, we get
37 + 23 = 30 + 7 + 23
Using ability to add a single digit to a number (e.g. by counting using the ten fingers), 7 + 23 = 30
So we have
37 + 23 = 30 + 7 + 23 = 30 + 30
Here is the tricky part. Hopefully, at 3rd grade, they can recognise the above can be evaluated by addition of single digit numbers: 3+3=6, so 30+30 = 60.

Answer 3

37 + 23 = 30 + 7 + 20 + 3 = 30 + 20 + 7 + 3 commutative property allows you to rearrange addition
= 30+20+10 = 60

Answer 4

Guessing here, but if you know 30 + 7 = 37 and you know 20 + 3 = 23....taking the 7 + 3 which makes 10, it turns it into a simpler 30+20+10 equasion which can be done in their head instead of the "carrying the one" method.
I agree, knowing 30+7 =37 doesn't help much. There are much easier ways to teach addition.

Answer 5

I think TG has the only really logical expression of a reason...it allows you to do the 30+7+20+3...37+20 is easy, 57. 57+3 is easy, 60.

This new math crap, though, is just beyond me. In reality, knowing the 30+7 has nothing to do with 37+23, because if you add them using basic math, then you'd have the following

37
23
'''''''''
60

So, you might as well ask, what about knowing 7+3=10 and 3+2=5 makes it easier? I don't get why they try and muck up the most basic element of math. It's a science....why do they try and tart it up into something else?

Answer 6

37 + 23= 60
3+7= 10
2+3= 5 = 15

Answer 7

Because then you can write 37+23 as 30+7+23 (just substitute 37 with 30+7. You can easily then see that 7+23=30, so 30+7+23=30+30=60.

Answer 8

because in third grade it is easier to add 30 + 30 that to add 23 +37

23 + 37
= 23 + (7 + 30)
= (23+7) + 30
= 30 + 30
= 60

Answer 9

The method for finding the solution to 30 + 7 = 37 is exactly the same as the 37 + 23 = 60. I suspect that the point of the question is to show the children that the size of the numbers has no impact on finding the solution. For example, if the question had been 3,153,247 + 1,234,567 = ? would the process be any different? No.

Answer 10

because you in 30 +7 you have a number with the multiple of 10 (30) so it is easier. 30+7=37. so in th problem 37+23 you can do 30+20 first (50) and then add the 7+3 next (10). then add 50+10=60. tada.

Answer 11

I know what they mean, and I know what the teacher is trying to teach his/her students. It's really hard to explain, especially to 3rd graders.

I think the same way.
What you do is, 30+7=37.... so what you do to figure out 37+23, is you just add 20 to 37.
Person thinking.
"Okay, so, 30+7=37... so 37+23 is the same thing except it's adding 20 to the final answer."

As I said, it's really hard to explain. The teacher shouldn't have explained it in that way if he/she did. All it does is confuse the students. They will eventually get it them selves.
Just like I did. Some students may catch on to it, but others may not and be left out in the hanging not knowing wth is going on.