Mental Math Starting at the Left

Welcome to Mental Math Quest: Starting at the Left!

Solve two‐digit addition problems using a left‐to‐right strategy. Instead of starting with the ones, add the tens first then the ones.

Multiple Choice Starting at the Left Practice

Mental Math Practice: Starting at the Left

Practice mental addition by starting at the left. For example, to solve 48 + 27 in your head, add the tens first (40 + 20 = 60) and then the ones (8 + 7 = 15) to get 75.

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"Starting at the Left" Mental Math Strategy:

When performing addition mentally, starting with the leftmost digits (tens place) simplifies the process by breaking numbers into manageable parts. Here's a step-by-step breakdown:

Steps:

  • Decompose Numbers: Split each number into tens and units.

Example:

  • 48=40+8
  • 27=20+7
  • Add Tens First:
    Combine the tens places.
    40+20=60
  • Add Units Next:
    Combine the units places.
    8+7=15
  • Combine Results:
    Add the two sums together.
    60+15=75

Why It Works:

  • Avoids "carrying over," which can be tricky mentally.
  • Focuses on larger chunks first (tens), making calculations easier to track.

Examples:

  • 55 +28: Tens: 50+20=70 Units: 5+8=13Total: 70+13=83
  • 35 + 49: Tens: 30+40=70 Units: 5+9=14 Total: 70+14=84

Practice Solutions:

Try These in Your Head:

  • 35+49=
  • 53+28=
  • 26+47=
  • 19+37=
  • 15+65=
  • 47+28=
  • 55+29=
  • 44+27=
  • 19+63=
  • 36+49=