Multiply and Divide Whole Numbers explain what to do and how to do it

2 answers:

8 0

Multiplication is a simple way of adding
For example 6x8 is the same as 8+8+8+8+8+8

Any number multiplied by 1 is itself E.g 4x1 = 4

Multiplying by 2 is just doubling

Multiplying by 10 is adding a 0 to the original number

If it is a big number that you do not know how to multiply mentally split it up
E.g 17x13
Split 13 into 10 and 3
17x10= 170
17x3= 51
Then add these numbers
221

If you ever get stuck, use the long method, add them instead, you will get to the right answer but it will take longer

Dividing is not as simple
Like multiplication dividing by one will leave you with the same answer

Dividing by two means you half the number, which may give you a decimal

Bigger numbers are trickier, and you may be allowed to use a calculator for numbers
Below are a number of links, these websites will teach you how to improve your multiplication and division skills:

http://www.bbc.co.uk/schools/gcsebitesize/maths/number/decimalsrev3.shtml

https://m.youtube.com/watch?v=XiXeu9FxAcQ

https://www.tutorialspoint.com/multiply_and_divide_whole_numbers/multiplication_as_repeated_addition.htm

alexandr402 [8]3 years ago

4 0

Multiplication:
It is like addition. For example, 1+1+1+1 is the same thing as 1 x 4, but multiplying is faster.

Division:
It is the opposite of multiplication. For example, 12/4=__. All you need to know is what times 4 equals 12, and the answer to that is 3. So the answer is 3.

You might be interested in

In the isosceles △ABC m∠ACB=120° and AD is an altitude to leg BC . What is the distance from D to base AB , if CD=4cm?

snow_lady [41]

If ΔACB is an isosceles triangle, then ∠A ≅ ∠B and AC ≅ CB

Since ∠C = 120° and ∠A + ∠B + ∠C = 180°, then ∠A = 30° and ∠B = 30°

Next, look at ΔADB. ∠A + ∠D + ∠B = 180°, so ∠A + 90° + 30° = 180° ⇒ ∠A = 30°

Now look at ΔADC. Since ∠A = 30° in ΔACB, and ∠A = 60° in ΔADB, then ∠A = 30° in ΔADC per angle addition postulate.

Now that we have shown that ΔADB and ΔADC are 30-60-90 triangles, we can use that formula to calculate the side lengths.

CD = 4 cm (given) so AC = 2(4 cm) = 8 cm

Since AC ≅ BC, then BC = 8 cm. Therefore, BD = 4 + 8 = 12 by segment addition postulate.

Lastly, look at ΔBHD. Since ∠B = 30° and ∠H = 90°, then ∠D = 60°. So, ΔBHD is also a 30-60-90 triangle.

BD = 12 cm, so HD = $\frac{12}{2}cm$ = 6 cm