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For multiplication, just break it down into small bits in pieces, especially easy numbers like 2, 3, 5, 10, and 12. And then just multiply those instead. If needed, you can also use this: ac + bc = c(a+b)

For example, 12 * 320 = 12 * 4 * 8 * 10, which is 48 * 8 * 10. Okay now, you have to multiply 48 and 8! Then you break that down. 48 * 8 = (40 * 8) + (8 * 8).

That is 320 + 64, or 384. Then multiply that by 10. You get 3840! It may take some practice, but when you succeed, you will be amazing!

I have to say, pretty much the same for division.

Q: How can you multiply and divide in your head without using a calculator?

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Divide the numerator by the denominator

How about using a calculator!

Multiply by 0.9144

Multiply both numbers by five- to get the fraction 85/100... which is 85%

You multiply the number together - using a calculator if needed.

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Divide the numerator by the denominator

Multiply the numerator of the fraction by 100 and then divide (using long division if needed or a calculator) by the denominator.

% rate:1. Divide 17 by 20.2. Multiply the quotient by 100%= (17 ÷ 20) x 100%= 0.85 x 100%= 85%

by using a calculator

How about using a calculator!

with your brain... Or the old-fashioned way -by counting it out on your fingers.

Multiply the whole number times the numerator. Divide the product by the denominator.

you divide 3 by 5 :P

Multiply by 0.9144

Two choices: -- Multiply (the number) x (the percent using the percent % key). -- Multiply (the number) x (the percent), then divide the answer by 100. Either way, the claculator displays that many percent of that number.

Multiply both numbers by five- to get the fraction 85/100... which is 85%

Calculate perimeteter of the semicircle then divide mathematically by seven using a calculator and then using that value and a divider or compass divide the semicircle.......