Math Lessons

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.

Suppose you want to add the fractions 3⁄7 and 4⁄5.
To get the numerator of the answer, cross-multiply. In other words, multiply the numerator of each fraction by the denominator of the other. continue reading…

Suppose you want to add 12.96, 3.5 and 8.
Line up the decimal points.
Begin adding from the right-hand column. Treat the blank spaces after 3.5 and 8 as zeroes.
Add first column.
Continue to the left.
Complete the problem column by column, and at the end, put the decimal point directly below the others. continue reading…

Suppose you want to find 45 divided by 3.
Start off by writing the problem like this.
To begin, ask how many times 3 goes into 4 — that is, what’s 4 divided by 3? continue reading…

Suppose you want to subtract 83 – 56.
Begin subtracting in the ones column: 3 – 6.
Because 3 is smaller than 6, you need to borrow from the tens column.
Subtract 1 from the 8 replacing 8 with a 7.
continue reading…

Suppose we want to add 26 and 79
Stack the numbers one on top of another so that the ones digits line up in a column and the tens digits line up in another column.
Add column by column, starting from the ones column on the right. continue reading…

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. continue reading…

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. continue reading…