Khan Academy Wiki

The Multiplying decimals 1 exercise appears under the 5th grade (U.S.) Math Mission, 6th grade (U.S.) Math Mission, Arithmetic essentials Math Mission, Pre-algebra Math Mission and Mathematics I Math Mission. This exercise practices basic multiplication involving decimals.

Types of Problems[]

There is one type of problem in this exercise:

  1. Multiply the numbers: This problem asks a multiplication problem. The user is expected to find the product and put it in the appropriate space.
    Multdec1

    Multiply the numbers

Strategies[]

This exercise is easy to get accuracy badges because except for the decimal they are just multiplication problems. The speed badges are also easy because almost all the problems have few decimal places.

  1. A calculator might actually slow users down on these problems.
  2. All problems are multiplying a whole number by a decimal and the vast majority have only one number after the decimal place.
  3. If users multiply by a number with one spot after the decimal, multiply the numbers (as if there were no decimal) and then move the decimal one spot left.
  4. There are two problems where the decimal number has more than one spot after the decimal point, but these are 0.25 and 0.75 which are easy to analyze as quarters or three-quarters.

Real-life Applications[]

  1. Decimals appear in every-day media to display information to consumers.
  2. Decimals are very common in shopping. Price tags, food labels, and receipts all contain decimals.
  3. At gas pumps, decimals are used to show how much gas is pumped and much it costs per gallon.