Khan Academy Wiki

The Multiplying decimals 3 exercise appears under the 6th grade (U.S.) Math Mission, 7th grade (U.S.) Math Mission, 8th grade (U.S.) Math Mission, Algebra basics Math Mission, High school geometry Math Mission and High school statistics and probability Math Mission. This exercise practices multiplication of decimals. There are numbers with various amounts of decimal places, and which involve multiple lines of work via the standard algorithm.

Types of Problems[]

There is one type of problem in this exercise:

  1. Find the product: This problem simply asks for the product of two decimal numbers. The user is expected to find the correct answer and write it in the available spot.
    Md3-1

    Find the product

Strategies[]

This exercise is easy to get accuracy badges because the algorithm itself is familiar from earlier topics. The speed badges are hard unless one uses a calculator.

  1. users do not need to line up decimal points to multiply decimals.
  2. Multiply the numbers as if there were no decimals, then count the decimal places users will need on the final answer. This works because each decimal point is like dividing by a copy of ten.
  3. A calculator goes against the spirit of practicing complicated multiplication problems, but can dramatically improve speed.

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.