What is the multiplication table of a half?

Answer 1

1 half = 0.5

2 halves = 1

3 halves = 1.5

4 halves = 2

5 halves = 2.5

6 halves = 3

7 halves = 3.5

8 halves = 4

9 halves = 4.5

10 halves = 5

11 halves = 5.5

12 halves = 6

etc.

New answer from MathMojo:

What is the multiplication table of half?

There is no "table" as such. At least none that is really useful. It turns out that "tables" are a pretty bad way to learn any multiplications for the following reason;

Memorizing a table by rote gives you the feeling that math is just a bunch of random facts that you have to learn, "or else..." This is the typical way schools beat you over the head with something that should otherwise be enjoyable.

Instead of helping schools dumb you down, think of multiply by half this way:

When you see a multiplication sign, think of the word "of." So "1/2 times 4 "becomes, "one half of 4." You know what one half of 4 is, right?

When you get to an odd number, think of the next lowest number, and do the same, but tack on the word, "and a half" at the end of the answer.

For example, when you see 1/2 times 7, think, "one half times 6". You know the answer is 3 (if you don't, you can even do it on your fingers until it becomes automatic), so say "three...and a half."

You tack on the extra, "and a half" because there was a half left over after you took half of the odd number.

What if the question is posed as "9 times 1/2" instead of "1/2 times 9"? Simply reverse it in your mind. Remember that multiplication is commutative (that means that you can reverse the numbers on each side of the multiplication sign). You can do that for the simple reason that four groups of three will give you the same results as three groups of four. That goes for all arithmetical number (all the numbers you will be dealing with for a long time).

So, "9 times 1/2" becomes "1/2 times 9", and you do it just like above. Take half of 8, and tack on "and a half." That would be "four and a half."

What if you were multiplying a larger number by one half? How about 67* 1/2?

First, think - "One half of seven." That would give you three and a half. Then, for the tens column, think - "one half of 6" which would give you 3 in the tens column. That would give you a total of 33 and a half. How easy was that?

What if there was an odd number in the tens column, or in one of the higher columns?

Let's say the problem was 97*1/2. Proceed as above. When as you are doing the seven, you'd normally think, "three and a half." In this case, though, you see that the number in the next highest column is going to end in "and a half" also.

But what is that half of? That is not "a half of 1" because that 9 is not in the ones column, is it? It is in the tens column. It's half of ten. That means it is 5. So that 5 would have to go into the ones column.

In other words, when you get to higher columns than the ones column, you don't tack on "and a half." Instead, you add a five to the next lowest column.

So in our example of 97*1/2, we know the final answer ends in "and a half." In the ones column, we'd have the three (from half of seven) plus 5. That means we put an 8 in the ones column.

Now for the tens, we have half of 9. Well, we've already taken care of the "and a half" part when we added the 5 to the ones column, so we just have to put a 4 in the tens column. That would make the product 43 1/2. That would be correct. 97*1/2 = 43 1/2.

Always check your answer. To check multiplication by 1/2, multiply the answer by 2. Is 43 1/2 times 2 equal to 97? It is on my planet, so your answer is right.

Try one more. 583 * 1/2

• half of 3 is 1 and a half. When you look at the next column, you will see that it's even, so you won't have to add 5 to that 3. So we know the units column is 1, followed by "and a half."

• Half of 8 is 4. But when you look at the next highest column, you will see that it is odd, so you will have to add 5 to that 4. That makes 9 as the answer in the tens column. So far our answer is 91 1/2.

• Half of five is 2 and a half, but we've already taken care of the half by adding that 5 to the 4 in the tens column, so we only have to put a 2 in the hundreds column, and then we're done. The answer to 583 * 1/2 is 291 1/2. Check it

There are two more things you may come across. One of them is "what do you do when there is a zero in the multiplicand?" (that's the number that is being multiplied). The other is "what do you do if you have to add a 5 to a number higher than 4; say 7?"

With a little imagination you can figure that out yourself. I don't want to deprive you of working it out and enjoying the feeling of accomplishment you'll get when you do.

This is not the method you will be taught in school. It is a lot better than that method. Learn it now and surprise the heck out of your teacher or parent. Of course, even though you will be faster than them at multiplication by 1/2 if you do it this way, they will not be used to it, and may be afraid of it. (There, there, little teacher, it's nothing to be afraid of, it's simple thoughtful multiplication. Imagine that!)

If you learn this way though, you will have no trouble at all when you learn the inferior, school way. You will understand it better than the other students, because you've got another viewpoint, and that is always better.

Keep this in mind - you may go to a typical school that makes you "show your work." You don't have any written work to show this way, do you? So learn it this way first, but then, for school, learn it their way. Don't fight the system (I'll be doing that for you). Make sure you give 'em what they want (show the work when you learn their method) and they'll give you what you want (good grades and they'll leave you alone.)

Having more than one way to do any math problem will automatically make you better at both, though.

Can I tell you a secret? Even though this way is better than the one you learned in school, there is still an infinitely better way to multiply by 1/2, and it's a lot easier. It works from right to left, instead of from left to right. So you won't be starting with the "chump change" first - you'd start with the greatest number. You can also do it faster mentally than most people can write the numbers down, or put them in a calculator. So you'd have the answer before they actually started working on it.

A first grader can learn this if they have some help from an adult.

How can you learn it? Go to the link below for learn2multiply, and sign up for the free video about multiplication by 5. It is basically the same thing as what you learned above, but with a tiny tweak. You will know it when you see it.

Have fun, and don't learn with tables until you understand what you are doing.