Question

How do you round 105 to the nearest hundred?

Answer 1

100

Explanation:

Showing what I call the cut off point (in red)

In your mind only write the number as:

`1" "color(red)(|)" "0" "5`
`" "color(white)(.)color(red)(uarr)`
`color(red)("cut off point")`

The digit to the right of the cut off point is less than 5 so we round down. That is, change all the digits to the right of the cut off point as 0 so:

105 is 100 to the nearest one hundred.
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
`color(blue)("Foot note")`

If the digit to the right of the cut off point had been 5 or more then we would have 200 to the nearest one hundred

Suppose it had been 163

6 satisfies the condition of 5 or more so the digit to the LEFT of the cut of point has 1 added to it.

Consider to the nearest 10

`12 -> "nearest 10 "=10` Rounding down
`13 -> "nearest 10 "=10` Rounding down
`14 -> "nearest 10 "=10` Rounding down

`15 -> "nearest 10 "=20` Rounding up
`16 -> "nearest 10 "=20` Rounding up
`17 -> "nearest 10 "=20` Rounding up
`18 -> "nearest 10 "=20` Rounding up
`19 -> "nearest 10 "=20` Rounding up
`20 -> "nearest 10 "=20` No rounding
`21 -> "nearest 10 "=20` Rounding down
`22 -> "nearest 10 "=20` Rounding down
`23 -> "nearest 10 "=20` Rounding down
`24 -> "nearest 10 "=20` Rounding down

`25 -> "nearest 10 "=30`