# Rounding and difficult nines

When rounding up 9's you have to be careful.

If you round a 9 to 10 think of it as adding 9+1

 9 +1 10

You put a zero in the first column and add 1 to the next.

Example 1

Round 43.299 to two decimal places.

You would answer this as follows:

43.299 round to two decimal places

43.2ul9\9 underline the digit (of 2^(nd) decimal place)

43.2ul9\9 look next door

9 It's five or more so you raise the score (round up)

43.2cancel9        9 becomes 10

43.30           add 1 to the next column and put a zero in the last column.

43.299 rounded to 2 D.P. =43.30

Example 2

Round 34.997 to two decimal places.

You would answer this as follows:

34.997 round to two decimal places

34.9ul9\7 underline the digit (of 2^(nd) decimal place)

34.9ul9\7 look next door

7 It's five or more so you raise the score (round up)

34.9cancel9             9 becomes 10

34.cancel9cancel9           But if you add 1 to the next column that becomes 10.

35.00                Add one to the next column.

34.997 rounded to 2 D.P. =35.00

Example 3

Round £19.90 to the nearest £1.00

£19.90  rounded to the nearest unit of 1

1ul9\.90   underline the digit (units 1)

1ul9\.90   look next door

9           It's five or more so you raise the score (round up)

1cancel9       9 becomes 10

20          Add 1 to the next column and put a zero in the last column.

£19.90 rounded to the nearest £1.00 is £20

Example 4

Round £99.98 to the nearest £1.00

£99.98   round to the nearest unit of 1

9ul9\.98 underline the digit (units 1)

9ul9\.98 look next door

9  It's five or more so raise the score (round up)

9cancel9        9 becomes 10

cancel9cancel9      But if we add one to the next column that becomes 10

100       Add one to the next column.

£99.98 to the nearest £1.00 is £100

Example 5

Round 5.9999 to 3 decimal places

Round 5.9999 to 3 D.P.

5.99ul9\9   underline the digit (3 D.P.)

599ul9\9    look next door

9        It's five or more so you raise the score (round up)

5.99cancel9         9 becomes 10

5.cancel9cancel9cancel9    but if you add one to the next column that becomes 10

6.000          now add one to the next column.

5.9999 to 3 decimal places is 6.000