How do you do long multiplication??

Question

For instance what is:

256
x 23

or

256
x123

Please show working out? I have forgotten how to work out long multiplication by hand. I need to know in preparartion for a job interview tomorrow that is going to involve a few numeracy and written tests.

Thanks

Answer 1

http://www.wikihow.com/Do-Long-Multiplication

Answer 2

Are you looking for a fast way to do long multiplication in your head, or will pencil and paper do? I can show you the pencil and paper way, and maybe explain a little about how it works, but not much more than that. First, let me ask, do you know how to multiply a 3 digit number by a 1 digit number? (say 373 x 7)? If not, there are three things that you need to know. 1) A number multiplied by 10 is just the same number with a "0" added at the end (i.e. 5 x 10 = 50, 12 x 10 = 120, 12345 x 10 = 123450). Similarly, a number multiplied by 100 is just the same as adding "00" at the end, (3 x 100 = 300), multiplying by 1000 adds "000", etc. 2) Multiplication has a "distributive" property. (i.e. (a + b) x c = (a x c) + (b x c) -- You could break up 10 x 5 into (5 + 5) x 5, which would be (5 x 5) + (5 x 5) = 25 + 25 = 50, if you wanted to. 3) When you are multiplying 3 numbers together, you can change the order. (i.e. 5 x 6 x 7 = 5 x 7 x 6) What you do in long multiplication is distribute the numbers into numbers that are multiples of 1, 10, 100, etc so that it is easier to multiply the individual numbers. It is as easy to multiply something by 300 as it is to multiply something by 3. Just add 00 to the final answer. So lets start by breaking 373 into numbers that are easier to multiply. 300, 70, and 3. (373 = 300 + 70 + 3) So 373 x 7 = (300 + 70 + 3) x 7 = (300 x 7) + (70 x 7) + (3 x 7) Each of these problems are easier to solve. Forget the extra zeros at the end of the number and do single digit multiplication 300 x 7 = 2100 (add 2 zeroes to 3 x 7) 70 x 7 = 490 (add 1 zero to 7 x 7) 3 x 7 = 21 2100 + 490 + 21 = 2611 Once you are able to multiply 3 digit numbers by 1 digit numbers, then you apply the same approach to each digit in the second number. Consider your original example 373 x 567 Take the second number, and add it up by each digit 500 + 60 + 7 373 x 567 = 373 x (500 + 60 + 7) = (373 x 500) + (373 x 60) + (373 x 7) = (373 x 5 and add two zeros) + (373 x 6 and add a zero) + (373 x 7) You've essentially gotten this down to 3 problems of a 3 digit number times a 1 digit number. Let's do each one at a time (373 x 5) = (300 + 70 + 3) x 5 = (300 x 5) + (70 x 5) + (3 x 5) = 1500 + 350 + 15 = 1865 (373 x 6) = (300 + 70 + 3) x 6 = (300 x 6) + (70 x 6) + (3 x 6) = 1800 + 420 + 18 = 2238 We already did (373 x 7) = 2611 So since we need to add zeros to the two above, you ultimately have 373 x 567 = (373 x 500) + (373 x 60) + (373 x 7) = 186500 (don't forget to add the zeros) + 22380 + 2611 186500 + 22380 + 2611 = 211491 (You have probably seen long multiplication that looks like 373 x 567 ---------- 2611 22380 (this is where the extra zeros come from) 186500 ------------ 211491 So that's why long multiplication works.

Answer 3

~~256
~ x 23
---------
~~768
~512
--------
~5888

Multiple the first number (256) times the last digit of the second number (3). Then on the line below that multiply the first number (256) times the next digit of the second number (2) but start at the place below that digit, not at the far right. The far right is assumed 0. If there was a third digit in the second number the furthest two right digits would both be 0s, and so forth.
Then you add the two products down and you have your total. (Ignore the ~'s. They are there to space the problem out correctly.)

Answer 4

256
x23

Step 1: Multiply all the numbers on the top line by the 3 from the bottom line.
Step 2: Add a 0.
Step 3: Mulyiply all the numbers on the top line by the 2 on the bottom line.
Step4: Add the answers yo got from your multiplication.

256
x 23
-------
768
+5120
----------
5888

Hope this helps

Answer 5

First multiply the top figure by the units of ten in this case the 2.
as they are units of ten you must place a zero in the answer first.

i.e
256
23 X
---------
0 Then multiply by the 2

256
23 X
--------
5120

Now multiply the top figure by the single units i.e the 3

256
23X
---------
5120
768
--------- now add the 5120 to the 768 and this is your answer


256
23 x
--------
5120
768
--------
5888


In the Second sum you would start by adding 2 zeros, multiplying the top figure by the hundreds then on the next line add 1 zero and continue as before.

256
123 X
---------
25600
5120
768 +
---------
31488
---------

Answer 6

This Site Might Help You.

RE:
How do you do long multiplication??
For instance what is:

256
x 23

or

256
x123

Please show working out? I have forgotten how to work out long multiplication by hand. I need to know in preparartion for a job interview tomorrow that is going to involve a few numeracy and written tests.

Thanks

Answer 7

Ignore the dotted lines, they're to put things in the right places.
Q..1.
....256
x... 23 First multiply by the 3
---------
.....768 Now by the 2 (1st put a '0' under the 8).
...5120
--------- Now add them up.
...5888 Answer.
----------

Q..2.
.......256
..x...123
----------- Same again..start with the 3
.......768 Then the 2 (add the '0' at the end first).
.....5120 Now by the 1 (Add 2 '0's at the end first).
...25600
------------ Add them up.
...21488 Answer.

Good luck.

Answer 8

256
x23
768
5120
5888
Firstly multiply 256x 3 ans 768
then add a nought under the8 and multiply256x2 ans 5120, then add the two together 5888

256
x123
768
5120
25600
31488
multiply 256x3
add 0 and multiply 256x2
add2 noughts256x1 and add them together.
Good luck tomorrow.

Answer 9

256
x 23
_______
0768
5120
___________
5888

Step 1: Multiply 3 by 6 = 18 (Write down 8 and carry over 1 to 5)
Step 2: Multiply 3 by 5 = 15 plus 1 that you carried over, you'll get 16. (Write down 6 and carry over 1 to the number 2)
Step 3: Multiply 3 by 2 = 6 plus 1 that you carried over, you'll get 7. That's how you get the 768.

Step 4: Write 0 under #8

Step 5: Multiply 2 by 6 = 12 (Write down 2 under the # 6 in 768 and carry over 1 to #5)

Step 6: Multiply 2 by 5 = 10 plus 1 that you carried over, you get 11. Write down 1 under 7 and carry over 1 to 2.

Step 7: Multiply 2 by 2 = 4 plus the 1 that you carried over, you'll get 5. (Write down 5 to the left of #2)

Step : Now you can do the simple addition 768 + 5120 = 5888

I hope this helps you in your job interview!

Answer 10

256 x 10 = 2560 + 2560 = 5120
256 x 3 = 768
3120 + 768 = 5888


256 x 100 = 25600

add answers together

Answer 11

265
*23 multiply the 3 will all numbers on the top, if10 add the number to next number: this will give you the first #. (795)
-------
795
+5300 add a 0 under the 5, then multiply the 2 with all numbers, that will give you the (5300)
---------
6095 if you add the (795+5300=6059)


hope this helped a little. sorry im not really good at writing it out