Teaching Autistic Children 3-Digit Addition

Is your child ready for three-digit addition? I will explain how to deal with the first step: learning to add three digits to one digit.

Three-Digit Plus One-Digit Addition

The first place where you’ll begin is with the addition of three-digit numbers to one-digit numbers.
321 +  5 =
Explain to your child that, in the tens column, he’s adding three plus nothing, which is exactly the same as three plus zero. Suggest that he write a zero under the number in the tens column to assist him with that idea; this will help him to visualize more easily and readily that concept.
If your child is still writing zeros in the tens column in these kinds of equations, don’t stop him if it helps him.
After your autistic child succeeds in adding numbers without carrying, you will want to introduce the next step: the concept of carrying, or regrouping.

A Three-Digit Addition Challenge

If your autistic kid struggles with carrying numbers in addition problems, he’s not alone.
Teach him how to carry the one and then add it to the tens column. You and your child may run into a dilemma. Look at this:
51 +  8=  69
If your child is solving math problems like this thoughtlessly, it means that he just grew accustomed to adding a 1 to the tens column, and will likely add in a 1 even though there was no carried 1 in the tens column.
This might be unique to ASD, for autistic kids are prone to getting stuck in ruts on account of their rigid, black-and-white thinking fashion; they tend to assume that the math-related task can be done in only one way. They might struggle adjusting a procedure to fit the current circumstances.

How to Fix This

Try verbally guiding him through every math problem. For the equation above, ask: “1 plus 8 equal_______________. And what does 0 plus 5 equal?”
Instruct him to practice abundantly in solving equations requiring carrying and those that do not. Then, mix them up to further test whether he actually learned when to carry a 1 and when not to.
The repetition of switching back and forth will hopefully train him how to catch on the procedure to the kind of equation he is solving.
If your kid has had difficulties, it might take much more practice to master this. It’s a good idea to ensure he understands this concept well before proceeding to the next step of adding three digits to two digits.
If you are dead serious about the cause and cure for autism, read this article: How is Chronic Fatigue Syndrome Related to Autism, Asperger's, and Fibromyalgia?