This worksheet looks at the relationship between fractions and division. It is important that children understand that finding one half of a number is equivalent to dividing by 2, that finding one quarter of a number is the same as dividing the number by 4 and to find one fifth is equivalent to dividing by 5. Plenty of practice is needed with this before children go on to find, for example, two fifths, or three fifths of numbers.
Most of these questions should be calculated mentally, although rough jottings may help. It might be a help to remember that finding a quarter of a number can be found by halving and then halving again. A fifth can be found by dividing by ten and doubling the answer, although if the number is not divisible by 10 it might be easier to do a quick pencil and paper calculation.
Month: June 2009
Year 5 number worksheet: recognise tests of divisibility for multiples of 9 and 10
This maths worksheet is another in our set on rules of divisibility. Knowing these rules will really help children in their maths up to the end of High School and beyond.
The rule for dividing by 10 is the easiest of them all:
If the whole number ends in a 0 then the number is divisible by 10.
The rule for 9 is also easy, but it does require a little adding up:
Add up all the digits. If the total of the digits is divisible by 9 then the whole number will be.
Example: 2304
2 + 3 + 0 + 4 = 9
So 2304 is divisible by 9.
Example: 9630
9 + 6 + 3 + 0 = 18
18 is divisible by 9 therefore 9630 is also divisible by 9.
The second part of the worksheet asks which numbers are divisible by both 9 and 10. Probably the best way to do this is to ignore any numbers that do not end in a zero, then add up the digits of the rest and see if they come to a multiple of 9.
If they do, and the last digit is a zero, then they are multiples of both 9 and 10. Easy!!