# 3.NBT.A.3

Multiply one-digit whole numbers by multiples of 10 in the range 10–90 (e.g., 9 × 80, 5 × 60) using strategies based on place value and properties of operations.

## Summary:

By building on the knowledge of one digit by one digit facts and their knowledge of place value, students will multiply one-digit numbers by multiples of ten between 10 and 90.

## Understanding the Standard:

• Students may need a review of adding and subtraction with multiples of ten in order to secure their understanding of how such calculations affect the result in the sum and differences. They should make the connection that in adding or subtracting by multiples of 10, the only digit affected is the digit in the tens place.
• Students should be exposed to a wide variety of ways in which to multiply a one-digit number by a multiple of ten.
• The use of manipulatives and other technologies can assist students with these calculations.

## Questions to Focus Instruction:

• When multiplying by multiples of 10, are students able to identify and communicate the pattern shown in the products?
• Can students relate the patterns they observe in multiplication with the patterns found in addition and subtraction and then make a generalization connecting them all with one another?
• Are students able to fluently multiply one-digit by one-digit numbers mentally?

## Skills

Prior to: Students have had practice with concept of arrays for their introduction to multiplication. Students have had extensive practice with adding and subtracting by multiples of ten and discerning the patterns they find when doing so. This will expand students' knowledge of patterns found when adding and subtracting by multiples of ten and applies to multiplication as well. Go to 1.NBT.C.6.

At Grade Level: Students will calculate the product of any one-digit number when it is multiplied by a multiple of ten.

Beyond Grade Level: This understanding will be built upon in later levels to include concepts in division and eventually in their work with decimal numbers as well.