Left to Right
Part of the Numbers & Operations section of Coddy's Pre-Algebra journey. Lesson 8 of 60.
Addition and subtraction have the same rank, so neither goes first by rule. When both appear, work from left to right. 15 - 6 + 3: first 15 - 6 is 9, then 9 + 3 is 12.
The classic slip is adding 6 + 3 first, which gives 6. It goes wrong because the 6 is being taken away, and the 3 is being added; gluing them together subtracts the 3 as well. Reading the minus as part of the number it sits in front of keeps you safe: the line takes away 6 and adds 3.
Multiplication and division share a rank in the same way. On the board, though, division is a fraction bar, and the bar already shows exactly what is divided by what.
Challenge
Work out 30 - 12 + 4, left to right.
Try it yourself
Simplify the expression
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.
All lessons in Numbers & Operations
1Working on the Board
Your First AnswerType the Next LineOne Line at a TimeDots and BarsFriendly ProductsRecap: Board Work4Adding Integers
Adding Two NegativesDifferent SignsZero PairsAdding Several IntegersRecap: Adding Integers2Order of Operations
Multiply Before AddingLeft to RightParentheses FirstBrackets Inside BracketsThe Fraction Bar GroupsRecap: Order of Operations5Subtracting Integers
Add the OppositeSubtracting a NegativePlus and Minus in a RowDistance Between NumbersRecap: Subtracting Integers