Problem Solving In Decimals
Identical wedges weighing 0.25 kg each are made from a big cheese weighing 2.5 kg. To solve this problem we have to think: With 2.5 kg of big cheese, how many wedges of 0.25 kg can we obtain?
The whole cheese has been divided into equal parts, so in order to know how many wedges we can obtain, we should divide 2.5 kg by 0.25 kg: To solve this problem we should think: if Maria spent 3 times more than Vanessa than the money that Vanessa spent is 3 times less.
The bill for the meal is .32—which includes a tax of .64. So if they know how to multiply .64 by 2, the couple can figure out how much they should leave for the tip. Andy just sold his van that averaged 20 miles per gallon of gasoline.
He bought a new pickup truck and took it on a trip of 614.25 miles. Did Andy get better gas mileage with the new truck?
And just as there is a correct way to multiply and divide whole numbers, so, too, there is a correct way to multiply and divide decimals.
In the examples above, notice that each quotient still contains the digits 4469—but as another 0 is added to the end of each power of ten in the divisor, the decimal point moves an additional place to the left in the quotient.
In cases like this, you can use powers of 10 to help create an easier problem to solve.
In this case, you can multiply the The number that is being divided into the dividend in a division problem. divisor, 0.3, by 10 to move the decimal point 1 place to the right.
Multiplying decimals is the same as multiplying whole numbers except for the placement of the decimal point in the answer.
When you multiply decimals, the decimal point is placed in the The result when two numbers are multiplied. product so that the number of decimal places in the product is the sum of the decimal places in the A number that is multiplied by another number or numbers to get a product.