Kellen earned 133 coins in Fruit Ninja yesterday and 278 more today. How many coins has Kellen earned in the last two days?

Nov 16, 2016

Sometimes it is easier to add up numbers if they are in column form.

$133 + 278 = 411$

Explanation:

$\textcolor{b l u e}{\text{Starting point:}}$

$133$
$\underline{278} \leftarrow \text{ add}$
$\underline{\textcolor{w h i t e}{278}}$

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
$\textcolor{b l u e}{\text{RHS column - 1's}}$

Working from right hand side to left hand side $R H S \to L H S$

$\textcolor{red}{8 + 3} = 11$ so write it like this:

$1 \textcolor{w h i t e}{. .} 3 \textcolor{w h i t e}{. .} \textcolor{red}{3}$
$\underline{2 \textcolor{w h i t e}{. .} 7 \textcolor{w h i t e}{. .} \textcolor{red}{8}} \leftarrow \text{ add}$
$\underline{\textcolor{w h i t e}{2. .7 \ldots .} 1}$
$\text{ } \textcolor{w h i t e}{.} 1$

Note the 10 carried to the tens column as 1 of 10
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
$\textcolor{b l u e}{\text{The middle column - 10's}}$

Adding the middle column we now have $\textcolor{red}{3 + 7 + 1} = 11$

But as this is the tens column so we have 1 of 10 and 1 of 100.
This time we write:

$1 \textcolor{w h i t e}{. .} \textcolor{red}{3} \textcolor{w h i t e}{. .} 3$
$\underline{2 \textcolor{w h i t e}{. .} \textcolor{red}{7} \textcolor{w h i t e}{. .} 8} \leftarrow \text{ add}$
$\underline{\textcolor{w h i t e}{2. . .} 1 \textcolor{w h i t e}{. .} 1}$
1""color(white)(..)color(red)(1)

Note the 1 of 100's is carried over into the 100's column

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
$\textcolor{b l u e}{\text{The LHS column - 100's}}$

Adding the LHS column we now have $\textcolor{red}{1 + 2 + 1} = 4$

$\textcolor{red}{1} \textcolor{w h i t e}{. .} 3 \textcolor{w h i t e}{. .} 3$
$\underline{\textcolor{red}{2} \textcolor{w h i t e}{. .} 7 \textcolor{w h i t e}{. .} 8} \leftarrow \text{ add}$
$\underline{4 \textcolor{w h i t e}{\ldots} 1 \textcolor{w h i t e}{. .} 1}$
color(red)(1)""color(white)(..)1
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
So $\text{ } 133 + 278 = 411$