Question

Which property or properties of arithmetic do you use when you calculate 3×70 by first calculating 3×7 = 21 and then putting a zero on the end of 21 to make 210? Write equations to show which properties are used and where

Answer 1

The property used is the Associative property

3 × 70 = 3(70) = 3 (7×10) = (3×7) ×10

The formula is

a × bc = a (bc) = a (b×c) = (a×b) ×c