Question

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

Answer 1

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

`133+278=411`

Explanation:

`color(blue)("Starting point:")`

`133`
`ul(278) larr" add"`
`ul(color(white)(278))`

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
`color(blue)("RHS column - 1's")`

Working from right hand side to left hand side `RHS->LHS`

`color(red)(8+3)=11` so write it like this:

`1color(white)(..)3color(white)(..)color(red)(3)`
`ul(2color(white)(..)7color(white)(..)color(red)(8)) larr" add"`
`ul(color(white)(2..7....)1)`
`" "color(white)(.)1`

Note the 10 carried to the tens column as 1 of 10
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
`color(blue)("The middle column - 10's")`

Adding the middle column we now have `color(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:

`1color(white)(..)color(red)(3)color(white)(..)3`
`ul(2color(white)(..)color(red)(7)color(white)(..)8) larr" add"`
`ul(color(white)(2...)1color(white)(..)1)`
`1""color(white)(..)color(red)(1)`

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

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
`color(blue)("The LHS column - 100's")`

Adding the LHS column we now have `color(red)(1+2+1)=4`

`color(red)(1)color(white)(..)3color(white)(..)3`
`ul(color(red)(2)color(white)(..)7color(white)(..)8) larr" add"`
`ul(4color(white)(...)1color(white)(..)1)`
`color(red)(1)""color(white)(..)1`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
So `" "133+278=411`