Math Lessons » Multiplication

Decimal Multiplication

admin — Thu, 15 Apr 2010 14:45:43 +0000

Suppose you want to multiply 25.3 by 0.46.
Pretend that you’re multiplying numbers without decimal points:
Now you need to find out where the decimal point goes.
To do this, notice that 25.3 has one digit after the decimal point, and that 0.46 has two digits after the decimal point.
Place the decimal point in the answer so that it has three digits after the decimal point.

Multiplying Larger Numbers

admin — Fri, 19 Mar 2010 16:33:55 +0000

Suppose we want to multiply 57 by 13. First we multiply 57 by 3 to get 171 .
Next we multiply 57 by 1..
1 is in the tens column so it really means 10. We have to put a 0 directly under the 1 in 171.
Now we can multiply 57 by 1 to get 57.
To finish up, add the two products
So 57 multiplyed by 13 is 741.

Multiplying Large Numbers

admin — Fri, 05 Mar 2010 15:39:30 +0000

Suppose we want to multiply 45 by 8. Start by stacking these numbers one on top of another with a line underneath. Multiply 8 by 5 . 8 by 5 is 40 so write down the 0 and carry the 4. Next, multiply 8 by 4. 8 by 4 is 32 . We need to add the 4 that we carried over, which makes the result 36. Because 8 and 4 are the last numbers to multiply, we write down the 36, we don’t have to carry. We find that 45 multiplied by 8 is 360.