Dividing decimals using estimation

today in class we were talking about using estimation to devide decimals.

we did a question like this

for your class party you have to bring cup cakes. Cup cakes cost 30 cents each. Is ten dollars enough to buy 1 cup cake per person in your class? estimate then calculate.

how you answer the question is that u round the 30 cents either up or down to a friendly number with 10.

10.00 divided by 0.50=20

10.00 divided by 0.25=40

so the answer is between th numbers 20 and 40

when u calculate it you get

10.00 divided by 0.30=33

that would not be enough for our class

the next thing we did was we did another question like this

you and 3 of your friends buy a 1.36 liter jug of juice the 4 of u share the juice evenly. how much did each person get?

how u answer this one is the same. round the 1.36 to a number friendly with 4

1.60 divided by 4=0.4

1.20 divided by 4=0.3

so the answer is between 0.4 and 0.3

when u calculate u get 0.34 per person.

for the next question we used hundereds grids that look like these

how many small bottles of water (0.295L) will fit into a big bottle of water (1.89L)

u change 1.89 to 1.80 and 0.295 to 0.3
so 1.80 divided by 0.3= 0.6
the answer would be about 6 small bottles of water would fit in a big bottle of water
if u calculate th answer would be 6.4


For home work we had to do a and b of a question. estimate

a) 40.5 divided by 5=8.1
u change 40.5 to 40 and then divide by 5
40 divided by 5=8
the real answer is 8.1

b) 57.9 divided by 3=19.3
u change 57.9 to 60 then divide by 3
60 divided by 3=20

the real answer is 19.3

here is a link that can help u divide decimals


http://www.gamequarium.com/division.html

thank u for looking at the blog and commenting :)