Wikipedia:Reference desk/Archives/Mathematics/2014 January 19

= January 19 =

BODMAS
BODMAS MEDTHOD IS VERY CONFUSING FOR ME.CAN ANYONE EXPLAIN IT PLEASE? — Preceding unsigned comment added by G.gadhadharan (talk • contribs) 15:49, 19 January 2014 (UTC)


 * Did you see order of operations ? Did that not cover it ? StuRat (talk) 16:11, 19 January 2014 (UTC)

What part of it do you want explained? — Preceding unsigned comment added by Bliever1 (talk • contribs) 00:28, 20 January 2014 (UTC)

BODMAS is the easiest thing in the world.

Brackets, Orders, Division, Multiplication, Addition, Subtraction.

This is how you do it.

Step 1. Get an expression

Step 2. Eliminate the brackets by calculating the subexpression within the bracket using BODMAS (recursively)

Step 3. At this step there are no more brackets so you eliminate the "Order" or exponentials or roots by calculating the subexpression of the "Order" using BODMAS (recursively)

Step 4. Calculate the Divisions by calculating the numerator divided by the denominator. You may need to calculate the expression of numerator using BODMAS (recursively). You may also need to calculate the expression of the denominator using BODMAS (recursively). If there are multiple divisions then the direction of the division goes from LEFT to RIGHT

Step 5. Multiplications going from Left to Right. Because it is multiplication the direction is irrelevant but I go from Left to Right.

Step 6. Calculate the additions and subtractions going from Left to Right. Treat subtraction as addition of negative numbers.

Step 7. The end. That's all you need to do.

Oh I forgot, you need to understand the concept of recursion.

What my teacher did not teach me

My maths teacher did not teach me that


 * Multiplication and Division has the same level of priority
 * Addistion and Substraction has the same level of priority

Multiplication and Division

To understand why Division has the same priority as Multiplication, you need to convert Division into multiplication of a reciprocal

$$1 * 2 \div 3 * 4 \div 5$$

becomes

$$1 * 2 * (\frac{1}{3}) * 4 * (\frac{1}{5})$$

Now you can see division as multiplication. Just Multiple up the numbers from LEFT to RIGHT. You can do it on a calculator by tapping the following keys "1" * "2" / "3" * "4" / "5" =

Another example

$$1 \div 2 \div 3 * 4 \div 5$$

becomes

$$1 * (\frac{1}{2}) * (\frac{1}{3}) * 4 * (\frac{1}{5})$$

Tap the following keys on the calculator "1" / "2" / "3" * "4" / "5" =

Addition and Subtraction

$$1 + 2 - 3 + 4 - 5$$

becomes

$$1 + 2 + (-3) + 4 + (-5)$$

Again just Add up the numbers from LEFT to RIGHT

220.239.51.150 (talk) 09:39, 20 January 2014 (UTC)

For reference, our article is at Order_of_operations. Note that this is a convention that we often follow. There is nothing else that makes it the "right" interpretation. So, compared to the rest of mathematics, this is one part that is fairly arbitrary! Other types of notation also work just fine, see for example reverse polish notation. SemanticMantis (talk) 21:58, 20 January 2014 (UTC)