story problems

Question

MElaine bought 1/3 yard of material for $4.20 per yard. How much did the material cost in all?

Answer 1

Problems with fractions are tough until you break them down. The 1/3 yard really means one yard divided by three. Since one yard is $4.20 but we're dividing the yard by three, let's also divide the price by three. So $4.20 / 3 =

 

To make it a little simpler, for now let's ignore the decimal. (But we have to remember that we've ignored it so we can put it back when we're done!) So let's figure out 420 / 3 =

 

Three will go into 4 (the first digit of 420) one time with 1 left over. Let's combine that leftover 1 with the 2 (the second digit from 420) to make 12. Three goes into 12 four times. It won't go into zero at all, or zero times. Now just put the results together: 1… 4… 0...

 

But let's not forget the decimal. When placing decimals we always count from the right. Since it was two positions over in the original question we put it two positions over in our answer to get $1.40