Multiply a Decimal by a Decimal Mentally

Have students multiply the digits first, then count the places in both factors. Use the two missing factor sheets as a check that students can reverse the rule.

Multiply 24 pairs of decimals in your head, like 0.5 × 0.3 and 0.32 × 0.09, counting decimal places. Multiply the digits as whole numbers, then count the decimal places in both factors. The product has that many decimal places: 0.6 × 0.08 = 0.048. The directions on the page read: Multiply. Find each product in your head. An answer key is included.

Yes, both. We made it for 6th Grade decimal multiplication, and the page works the same whether it lands on a kitchen table or a center rotation. At home, most families go through it together and talk the answers out loud, and that talking is where most of the learning happens with multiply a decimal by decimal. In class it runs well as independent work while you pull a small group. Print one copy or thirty, whichever the day needs.

Add the decimal places in both factors. On Multiply a Decimal by a Decimal Mentally, 0.6 × 0.08 has 1 + 2 = 3 places, so the product is 0.048.

Taking part of a part leaves less than either part. On Multiply Decimals With Up to 3 Decimal Places, 0.4 × 0.003 = 0.0012, which is smaller than both factors.

Divide the product by the factor you know, or think of the digits first and then the places. On Missing Factors in Decimal Multiplication, 0.06 times a number equals 0.048, and 6 × 8 = 48, so the missing factor is 0.8.