+9675 Use PEDMAS(or BODMAS)
1 + 5 * 10
= 1 + 50 <--- evaluate multiplication first
= 51 <--- then evaluate addition.
+20 Left to right:
(1+5)×10=60
PEMDAS/BODMAS:
1+(5×10)=51
The average between the two results:
60+512=55.5
+9488 Be careful PkmnQ, there is only one correct way to do a math problem.
The correct order is parenthesees/brackets, exponents, multiplication and division, addition and subtraction. "Left-to-right" comes into play when you have division in the problem. When you reach the "multiplication and division" step, do it from left to right.
For example,
15/5 * 2 = 3 * 2 = 6
NOT
15/5 * 2 = 15/10 = 1.5 ← ERRR This is wrong!!!
Personally, I would rather just remember that only the thing immediately following the division sign goes in the denominator, instead of remembering "left to right." But maybe that is just me. 
But... "left to right" is not an alternative to PEMDAS... it is a part of PEMDAS .
