ABE Math Tutorials/Whole numbers/Long multiplication
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It won't come as a surprise, then, to find that multiplying big numbers is very similar to adding big numbers.
Here's another example, but with carrying.
This example is done mostly like the one above, except that we now have two digits to multiply (both the "2" and the "5" in 25). First, we multiply 406 x 5, just as before. Next, we multiply 406 x 2 -- but we must put the answer to this multiplication one space to the left of the answer above. Some people like to write an extra "0" on the end to hold this space, so that they don't forget. Once you have the two multiplications done, you add them together to get the final answer: 10,150.
Common mistake!When you are doing a long and complicated multiplication, it is easy to add the wrong digits together when you are calculating the final answer. Try to place your digits neatly, one under the other, so that you are adding all the ones' column together, all the tens', etc.
Ready for an even more complicated example? Try to multiply 306 x 1582 -- then see how your work compares with the example shown below:
Since we are multiplying by a 3-digit number, we will have three multiplications before we add up to get the final answer. Note that the third multiplication (ie. where we multiply 1582 x 3) is moved over two spaces to the left.Did you get 484,092 for your answer?
If so, try these multiplication problems on your own.
- 714 x 82 =
- 3054 x 60,416 =
- 989 x 170 =