# SP math question

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Why make tens first to add?

I don't understand the point.

If you add 18+6 why take 2 from 6 and make it 4, then add the 2 to the 8 to make it 10, then add the 10's and then add the 4 that is remaining

(18+6= 10+8+6= 10+ (8+2=10)+ (6-2=4)=10+10+4=24).

(18+6= 10+8+6= 10+14=24).

Why does a 1st grader need to do this? Is there something it helps with in later grades?

I understand the need to understand math conceptually, but if you understand that 18+6 is the same as 10+14 which is the same as 10+10+4......what does it matter which way your dc gets there? If your dc understand and prefers one method over another, why push making 10's?

What is conceptually wrong with adding your ones column and carrying your 10's over to the tens column and adding the tens. You have to understand place value to do either way.

And if it is all about speed, memorizing your facts will be just as fast as making 10's to add....

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Why make tens first to add?

I don't understand the point.

If you add 18+6 why take 2 from 6 and make it 4, then add the 2 to the 8 to make it 10, then add the 10's and then add the 4 that is remaining

(18+6= 10+8+6= 10+ (8+2=10)+ (6-2=4)=10+10+4=24).

(18+6= 10+8+6= 10+14=24).

Why does a 1st grader need to do this? Is there something it helps with in later grades?

I understand the need to understand math conceptually, but if you understand that 18+6 is the same as 10+14 which is the same as 10+10+4......what does it matter which way your dc gets there? If your dc understand and prefers one method over another, why push making 10's?

What is conceptually wrong with adding your ones column and carrying your 10's over to the tens column and adding the tens. You have to understand place value to do either way.

And if it is all about speed, memorizing your facts will be just as fast as making 10's to add....

It is a skill that will allow your child to add and subtract larger numbers mentally later on down the road, and with much more ease.

For example, if you are subtracting 384 from 500, and you are proficient at making 10's, you would figure that adding 6 would make 390, and 10 more would make 400, and 100 more would make 500, so the answer is 116 (making 100 is just another form of making 10). If you have practiced making 10's at a younger age, than by the time you are doing problems like this you will be able to do it much faster in your head than the time it takes me to explain it, and you could probably do it without even having to think about each step, you would just do it automatically. You would also be able to do it much, much faster than the time it would take to write the problem down and complete all of the borrowing and carrying needed with the traditional written method. The written method of borrowing is also much more difficult and much more complicated in terms of mental computation, since borrowing requires you to make 10's in a much more abstract way than the linear one I described.

The point of doing this on a smaller scale in first grade is to foster this kind of mathematical thinking from the get go, so your mind will become a "calculator" that will serve you well later down the road when the problems become more difficult. If you can learn to make 10's with small numbers, you will have the skills to do any addition or subraction problem.

I was never explicitly taught to think like this by any of my teachers, but it is how I naturally approached math. My second son also does math this way without any real instruction, it is just the way he thinks, and so Singapore Math can seem tedious to him at times, and we often just skip some of the instruction or review in the textbook. But, my oldest son does not think this way in terms of math, it doesn't come naturally to him, and so the explicit instruction and practice may seem tedious to me, but for him it is completely necessary. You just need to pay close attention to your child's reasoning and ability, and then you can tailor the program to fit their own needs.

HTH!

Edited by MyFourSons
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