Contributor: Rachel Lewis. Lesson ID: 12179

Uh oh! You're stuck on a desert island and you have to add coconuts and pineapples! You have no calculator, computer, or pencil! Learn how to quickly add in your head (even if you're not marooned)!

categories

## Arithmetic, Arithmetic, Operations and Algebraic Thinking

subject
Math
learning style
Visual
personality style
Otter
Intermediate (3-5)
Lesson Type
Skill Sharpener

## Lesson Plan - Get It!

Audio:
• How quickly can you solve 25 + 67 using just your brain?

Hurry, we need to know now!

The track team ran a total of 13 miles the first week of practice. They ran 24 miles the second week of practice.

• How many miles did they run in all?

Solve the problem on your own.

• Did you get an answer of 37 miles?

Great job!

• How fast did you solve the problem?
• Did you use paper and pencil or a calculator to find the sum?

To solve an addition problem quickly, you can use mental math. Mental math allows you to solve a problem without a calculator, computer, or pencil and paper.

Learn strategies that you can use to add one- and two-digit numbers with mental math. Read Mental Math Addition (Math-Only-Math.com).

When you solve an addition problem, you might use the thinking tricks from Addition Tips and Tricks from MathIsFun.com. Consider the following questions:

• Can you count up from a number or use the jump strategy?
• Can you add up to ten, do the tens last, or aim for ten?
• Would it be helpful to round the numbers in the compensation method?

Race to the Got It? section to use your new mental addition strategies!

Interactive Video