Do we need t use MDAS in math?

Answer 1

16 - 8 ÷ 4 + 3 x 2 = ?

If you just performed the actions in order left to right, you might think that the answer was 10. Since we know that multiplication and division come first the equation becomes 16 - (8 ÷ 4) + (3 x 2) = 20

For clarity, an order is necessary. MDAS (actually PEMDAS) is the one that was decided on.

Answer 2

MDAS looks like an abbreviation for "multiplication, division, addition, subtraction". You may need to use those operations in math.

It's part of the longer acronym PEMDAS, which adds parentheses and exponentiation. It's intended to be a mnemonic for what order the operations are performed in, but to be honest if you need a mnemonic to remember that you're already in trouble, particularly because it's not actually right (multiplication and division have the same priority, as do addition and subtraction).