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Multiplication: place value and area models

Multiplication: place value and area models

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Multiply 2-digit numbers with area models (practice) | Khan Academy

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If you're seeing this message, it means we're having trouble loading external resources on our website. If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked. To log in and use all the features of Khan Academy, please enable JavaScript in your browser.

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Multiplication - 2 Digits by 2 Digits | Math Playground

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Practice multiplying large numbers at MathPlayground.com!

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Operations

"Operations" mean things like add, subtract, multiply, divide, squaring, etc. If it isn't a number it is probably an operation.

But, when you see something like ...

... what part should you calculate first?

Start at the left and go to the right?
Or go from right to left?
Warning: Calculate them in the wrong order, and you can get a wrong answer !
So, long ago people agreed to follow rules when doing calculations, and they are:

Order of Operations

Do things in Parentheses First

Exponents (Powers, Roots) before Multiply, Divide, Add or Subtract

Multiply or Divide before you Add or Subtract

Otherwise just go left to right

How Do I Remember It All ... ? PEMDAS !

Divide and Multiply rank equally (and go left to right).

Add and Subtract rank equally (and go left to right)

So do it this way:

After you have done "P" and "E", just go from left to right doing any "M" or "D" as you find them.

Then go from left to right doing any "A" or "S" as you find them.

Pudgy Elves May Demand A Snack
Popcorn Every Monday Donuts Always Sunday
Please Eat Mom's Delicious Apple Strudels
People Everywhere Made Decisions About Sums

You may prefer GEMS ( Grouping, Exponents, Multiply or Divide, Add or Subtract).
In the UK they say BODMAS (Brackets, Orders, Divide, Multiply, Add, Subtract).
In Canada they say BEDMAS (Brackets, Exponents, Divide, Multiply, Add, Subtract).
It all means the same thing! It doesn't matter how you remember it, just so long as you get it right.

Examples

Example: How do you work out 3 + 6 × 2 ?

Multiplication before A ddition:

Example: How do you work out (3 + 6) × 2 ?

P arentheses first:

Example: How do you work out 12 / 6 × 3 / 2 ?

Multiplication and D ivision rank equally, so just go left to right:

A practical example:

Example: Sam threw a ball straight up at 20 meters per second, how far did it go in 2 seconds?

Sam uses this special formula that includes the effects of gravity:

height = velocity × time − (1/2) × 9.8 × time ²

Sam puts in the velocity of 20 meters per second and time of 2 seconds:

height = 20 × 2 − (1/2) × 9.8 × 2 ²

Now for the calculations!
The ball reaches 20.4 meters after 2 seconds
Exponents of Exponents ...

What about this example?

Exponents are special: they go top-down (do the exponent at the top first). So we calculate this way:
And finally, what about the example from the beginning?
297, 1566, 1572, 298, 1568, 381, 1570, 3854, 3855, 383

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"Operations" mean things like add, subtract, multiply, divide, squaring, etc. If it isn't a number it is probably an operation. But, when you see something like ... ... what part should you calculate first? Start at the left and go to the right? Or go from right to left?

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Complete
D.15
D.18
D.24
E.1
E.2
E.3

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Learn fourth grade math skills for free! Choose from hundreds of topics including multiplication, division, fractions, angles, and more. Start learning now!

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Hernando de Soto Biography for Kids - MrNussbaum.com

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After the winter, de Soto's expedition traveled southwest. On May 8, 1541, Hernando de Soto discovered the Mississippi River, although de Soto was not exactly thrilled with the finding. The Mississippi River was a huge, broad river that stood in the way of his expedition.

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Read about John Cabot

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John Cabot - Explorers for Kids and Teachers - FREE Lesson Plans for Teachers, Games for Kids

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John Cabot was disappointed, but he did claim what would become Canada for England. It was the first of many claims of Canada for England. Cabot explored the Canadian coastline, and named many of the harbors he found. He made a second voyage to North America, still looking for a back door to China.