Decimals

Use the same method as for whole numbers BUT MAKE SURE THE DECIMAL POINTS ARE LINED UP

eg.

· Ignore decimal points

· Multiply as normal

· Count how many digits AFTER decimal point in both numbers

· Count back

eg.

1 place (total

1 place of 2

places

back)

So answer = 8.88

Move the decimal point forward to make the number bigger by the same number of places as there are zeros

eg.

(10 has 1 zero, move point 1 place)

eg.

(100 has 2 zeros, move point 2 places)

eg.

(100 has 2 zeros, move point 2 places add extra zeros if necessary)

· Take the number you are dividing by and move the decimal point as many places as is necessary for it to become a whole number

· Move the decimal point on the other number, the same number of places

· Divide as in long division

eg.

0.13 is the dividing number so move the decimal point 2 places to become 13

Move the decimal point in 2.6 two places so it becomes 260. The sum is now

Same as with multiplying but move the decimal point backwards to make the number smaller

eg.

eg. etc

Rounding

The number of decimal places is the number of digits AFTER the decimal point

eg. 2.375 is to 3dp

To round off to a given number of decimal places:

· Count to the correct place

· Look at the next digit ONLY

· If it is 5 or more, round up

· If not, don’t round up

eg. 2.3746 to 2dp = 2.37

to 3dp = 2.375