CCSS.MATH.CONTENT.3.OA.C.7
Fluently multiply and divide within 100, using strategies such as the relationship between multiplication and division (e.g., knowing that 8 × 5 = 40, one knows 40 ÷ 5 = 8) or properties of operations. By the end of Grade 3, know from memory all products of two one-digit numbers.
This lesson should help 3rd grade students learn a simple, and magical method for multiplying by 9 up to the 10s place. Larger numbers are scary at times, but the number 9 has some magical properties that help it to be less scary!