Idiots guide to multiplication and dividing???

Question

I spent my years at school arsing about and copying my mates work....
Now I am 30 and need to know how to multiply and divide...
Anyone know where there are any self teaching guides on how to do it...??
I mean i can do basic stuff by adding and subtracting but if you asked me what 58 x 32 was or 78 / 23 then i wouldnt have the foggiest idea how to work it out!!
Help???
I need to learn this and have it lodged in my brain by next week!!

Answer 1

A few basic tips:

Anything multiplied by 0 is 0 (i.e. 0x1235248902348 = 0)
Anything multiplied by 1 is itself (i.e. 1x1235248902348 = 1235248902348)

Anything multiplied by 2 is the same as adding that number to itself.

Anything multiplied by 5 MUST end in a 0 or a 5 (0 if the number is even, 5 if the number is odd)

Anything multiplied by 10, just add a 0 to the end of the number

Anything multiplied by 11, add a zero to the end of the number, then add the original number.

(i.e. 5654 x 11 = 56540 + 5654)

When multiplying two 2-digit numbers like 58 x 32, you need to break it up into smaller bites. Write it one over the other as follows:

58
x32
------

Now we go from right to left, using the bottom number to multiply against the top number. First we do 2x8 which is 16. We put the 6 down in the ones place, and "carry" the 1 over to the left and place it above the five.

1
58
x32
-----
6

Now we multiply 2x5 which is 10, and we add that 1 that we carried, so it becomes 11. We put the 1 in the tens place, and carry the other 1 to the left. Since there's no number there, it drops down to the hundreds place.

58
x32
------
116

Now we multiply by the 3. But since the 3 is in the tens place, it's really multiplying by 30 (3x10). Remember what I said about multiplying by 10? Add a 0 to the number. So we put a 0 as a "place holder" first

58
x32
------
116
0

Now we multiply 3x8 to get 24. The 4 goes in the tens place, the 2 is carried over.
2
58
x32
------
116
40

Now 3x5 which is 15, then add the 2 so we get 17. The 7 goes in the hundreds place, and the 1 goes in the thousands place.

58
x32
------
116
1740

Now we add 116 and 1740 together and we get: 1856.


For division, that's harder to do in this format. If you would like, contact me and I can give you some private tutoring files that I put together for my students. They should help you.

Good luck!

Answer 2

Start With Multiplying: 25 X 2=
20 X 2 + 5 x 2=
40 + 10 = 50
Not so very difficult.

Next step a little moore complicated:
27 X 22=
27 x 20 + 27 x2=
20 x 20 + 7 x 20 + 20 x 2 + 7 x2=
400 + 140 + 40 + 14 = 594
Oldfashion calculation is done like this. The number to the right is called the multiplyer and the number to left is called the multiplcant.
You start with the oneers and multiply with all the oners teners and hundreds..... in the multiplicant. Next you take the teners in the multiplyer and multiplies with all the factors in the multiplicant an so on....

...............27x22
................54
..............54
..........= 594
Notice that you move the numbers one position to the
right right when multiplying with teners. When multiplying with hundreds you move to positins to the right, and so on...

Answer 3

For multiplication, try searching for Trachtenberg system. This is a bit tricky at first, but is a faster way to multiply

For division, first convert it to mixed fraction. Taking your example...

78 / 23 = 3 + 9/23 (i.e 23*3/23 + 9/23)

= 3 + 9 *10 / 23*10
= 3 + 0.1 * 90/23 (Just for your convenience)

Now, 23*3 = 69 and 23*4 = 92
90 is between the two numbers, but very near 92

So, you can safely assume...

= 3 + 0.1 * 39...
= 3.39....

Answer 4

Many people today use a calculator
58 times 32=1856
78 divide by 23=3 9/23 3.3913

Answer 5

split the sum up

e.g. 58 x 32

first do 58 x 10 which is 580
then multiply that total 580 by 3 which is 1740
So you now now what 30 x 58 is

Then do 2 x 58 which is 116

add 116 to 1740 and you get the total: 1856

This is what 58 x 32 is.


The same principle works for division.

If you need any more explanation please feel free to email me via my profile.

Answer 6

You need to go to your local WH Smith's (or equivalent) and get a copy of Letts Premier Maths Key Stage 2. Start with ages 9-10 or perhaps 10-11. These are straightforward books (£3.99 each) that explain mental and written methods. Please don't think that I'm being patronizing by suggesting books meant for young children. I'm a primary teacher and I believe that these books are an excellent place to start for anyone wanting to understand the basics of numeracy.

Answer 7

To use your example
________________________58
_______________________*32
_______________________------
multiply the units column first 116
then the tens____________1740 putting a zero at the end
_______________________------ to multiply by ten
.add them together________1856 to get the answer


The same goes for higher numbers
_________________________128
_________________________*427
________________________--------
multiply the units column first___896 zero
then the tens______________2560 to multiply by ten
the the 100's_____________51200 and 100
_______________________--------
add them together_________54656

As for division you need to guess how many whole times the number goes in to the tens column (in this case 0) any remainder has to be carried over to the units (to give 78) guess again how many times into that number (in this case 69) and multiply that out (to get to get 23 by 3), take it away and then repeat the process for the remainder and stop when you are happy you have enough decimals. To check the answer you can multiply them out.

___03.39_____the answer
_23/78.00
___69.00_____the 3
___--------
____9.0
____6.9______the .3
____--------
____2.10
____2.07_____the .09
____--------
____0.03

Answer 8

Try google for simple maths should come up with a few suggestions

Answer 9

Too late. Get a calculator.

Answer 10

try BBC bitesize, they have some really good methods for you to practise. Good luck.